Remote build on mac broken?

Hi there. I’ve been getting an error from UntrealBuildTool when doing a remote build on mac. I have been unable to find anything wrong from the logs, and had to revert to 4.19 for it to work.

This is the offending part of the logs, where UnrealBuildTool starts to perform 3 actions in parallel

CommandUtils.Run: Running: B:\Projects\Epic\UE_4.20\Engine\Binaries\DotNET\UnrealBuildTool.exe AR_Sturla IOS Development -Project=B:\Projects\Epic\Projects\AR_Sturla\AR_Sturla.uproject  B:\Projects\Epic\Projects\AR_Sturla\AR_Sturla.uproject -NoUBTMakefiles  -remoteini="B:\Projects\Epic\Projects\AR_Sturla" -skipdeploy -ini:Game:[/Script/UnrealEd.ProjectPackagingSettings]:BlueprintNativizationMethod=Disabled -noxge -NoHotReload -ignorejunk -log="C:\Users\joi\AppData\Roaming\Unreal Engine\AutomationTool\Logs\B+Projects+Epic+UE_4.20\UBT-AR_Sturla-IOS-Development_2.txt"
ProcessResult.StdOut:   Picking the default remote server ardev-mac-pro
ProcessResult.StdOut:   Doing date +"%s" && sysctl hw.memsize | awk '{print $2}' && sysctl hw.logicalcpu | awk '{print $2}'
ProcessResult.StdOut:   Execute took 00:00:00.2616826
ProcessResult.StdOut:   Remote time is 28.8.2018 14:27:27, difference is 00:00:00.1457027
ProcessResult.StdOut:   Doing echo $HOME
ProcessResult.StdOut:   Execute took 00:00:00.2479701
ProcessResult.StdOut:   Doing xcode-select --print-path
ProcessResult.StdOut:   Execute took 00:00:00.2585168
ProcessResult.StdOut:   Doing ls /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs
ProcessResult.StdOut:   Execute took 00:00:00.2959535
ProcessResult.StdOut:   Compiling with iPhoneOS SDK 11.4 on Mac ardev-mac-pro
ProcessResult.StdOut:   Doing rm -f /Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Binaries/IOS/AssetCatalog/Assets.car
ProcessResult.StdOut:   Execute took 00:00:00.2489492
ProcessResult.StdOut:   Command: -vzrltgoDe "ssh -i '/cygdrive/C/Users/joi/AppData/Roaming/Unreal Engine/UnrealBuildTool/SSHKeys/ardev-mac-pro/ardev/RemoteToolChainPrivate.key' -p 22" --rsync-path="mkdir -p /Users/ardev/UE4/Builds/F2770 && rsync" --chmod=ug=rwX,o=rxX --delete --files-from="/cygdrive/C/Users/joi/AppData/Local/Temp/tmp32F0.tmp" --include-from="/cygdrive/C/Users/joi/AppData/Local/Temp/tmp32F1.tmp" --include='*/' --exclude='*.o' --exclude='Timestamp' '/cygdrive' "ardev@ardev-mac-pro":'/Users/ardev/UE4/Builds/F2770'
ProcessResult.StdOut:   building file list ... done
ProcessResult.StdOut:   B/Projects/Epic/Projects/AR_Sturla/Intermediate/Build/
ProcessResult.StdOut:   B/Projects/Epic/Projects/AR_Sturla/Intermediate/Build/IOS/UE4/Development/AR_Sturla/
ProcessResult.StdOut:   B/Projects/Epic/Projects/AR_Sturla/Intermediate/Source/AR_Sturla.Build.cs
ProcessResult.StdOut:   B/Projects/Epic/Projects/AR_Sturla/Intermediate/Source/AR_Sturla.Target.cs
ProcessResult.StdOut:   B/Projects/Epic/Projects/AR_Sturla/Intermediate/Source/AR_Sturla.cpp
ProcessResult.StdOut:   sent 514674 bytes  received 116 bytes  68638.67 bytes/sec
ProcessResult.StdOut:   total size is 1687778385  speedup is 3278.58
ProcessResult.StdOut:   Command: -vzrltgoDe "ssh -i '/cygdrive/C/Users/joi/AppData/Roaming/Unreal Engine/UnrealBuildTool/SSHKeys/ardev-mac-pro/ardev/RemoteToolChainPrivate.key' -p 22" --rsync-path="mkdir -p /Users/ardev/UE4/Builds/F2770 && rsync" --chmod=ug=rwX,o=rxX --files-from="/cygdrive/C/Users/joi/AppData/Local/Temp/tmp32F0.tmp" --include-from="/cygdrive/C/Users/joi/AppData/Local/Temp/tmp32F1.tmp" --include='*/' --exclude='Timestamp' '/cygdrive' "ardev@ardev-mac-pro":'/Users/ardev/UE4/Builds/F2770'
ProcessResult.StdOut:   Doing sh tmp6404.tmp.sh && rm tmp6404.tmp.sh
ProcessResult.StdOut:   Execute took 00:00:04.0300232
ProcessResult.StdOut:   BatchFileInfo took 00:00:04.4839378
ProcessResult.StdOut:   Performing 3 actions (8 in parallel)
ProcessResult.StdOut:   Doing /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++  -fmessage-length=0 -pipe -fpascal-strings -fdiagnostics-format=msvc -fno-exceptions -fno-objc-exceptions -fno-rtti -fvisibility=hidden -Wall -Werror -Wdelete-non-virtual-dtor -Wshadow -Wno-error=shadow -Wundef -Wno-unused-variable -Wno-unused-value -Wno-unused-function -Wno-switch -Wno-tautological-compare -Wno-unused-private-field -Wno-invalid-offsetof -Wno-gnu-string-literal-operator-template -Wno-inconsistent-missing-override -Wno-unused-local-typedef -Wno-nonportable-include-path -Wno-nonportable-include-path -c -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.4.sdk -miphoneos-version-min=11.0 -O3 -gdwarf-2 -include "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/Build/IOS/UE4/Development/AR_Sturla/Definitions.h" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Algo" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Algo/Impl" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Apple" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Async" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Clang" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Containers" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Delegates" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Features" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/FramePro" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/GenericPlatform" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/HAL" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/HAL/Allocators" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Hash" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Internationalization" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/IOS" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Logging" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Math" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Misc" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Modules" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Modules/Boilerplate" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/ProfilingDebugging" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Serialization" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Serialization/Csv" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Serialization/Formatters" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Stats" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Templates" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/Traits" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/Runtime/Core/Public/UObject" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate" -I"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/Source" -x objective-c++ -fobjc-abi-version=2 -fobjc-legacy-dispatch -std=c++14 -stdlib=libc++ -fno-rtti -o "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/Build/IOS/UE4/Development/AR_Sturla/Module.AR_Sturla.cpp.o" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/Build/IOS/UE4/Development/AR_Sturla/Module.AR_Sturla.cpp"
ProcessResult.StdOut:   Upload took 00:00:00.4274576
ProcessResult.StdOut:   Execute took 00:00:02.2211854
ProcessResult.StdOut:   [1/3] Compile Module.AR_Sturla.cpp
ProcessResult.StdOut:   Doing sh -c '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++  -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.4.sdk -dead_strip -miphoneos-version-min=11.0 -Wl-no_pie -stdlib=libc++ -ObjC  -framework OpenGLES -framework UIKit -framework Foundation -framework AudioToolbox -framework AVFoundation -framework GameKit -framework StoreKit -framework CoreVideo -framework CoreMedia -framework CoreGraphics -framework GameController -framework SystemConfiguration -framework DeviceCheck -framework CoreMotion -framework AdSupport -framework WebKit -framework iAD -framework AudioToolbox -framework CoreAudio -framework AVFoundation -framework AudioToolbox -framework CoreAudio -framework AVFoundation -framework ARKit -framework CoreImage -framework ImageIO -framework CoreImage -framework Vision -framework CoreMedia -framework CoreVideo -framework AVFoundation -framework AudioToolbox -framework MediaToolbox -framework QuartzCore -framework Security -framework GameKit -framework StoreKit -framework DeviceCheck -framework OpenGLES -weak_framework QuartzCore -weak_framework Cloudkit -weak_framework MultipeerConnectivity -weak_framework Metal -L"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/PhysX3/Lib/IOS" -L"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/PhysX3/Lib/IOS" -L"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/FreeType2/FreeType2-2.4.12/Lib/ios/Device" -L"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/libPNG/libPNG-1.5.2/lib/ios/Device" -l"LowLevelPROFILE" -l"LowLevelAABBPROFILE" -l"LowLevelClothPROFILE" -l"LowLevelDynamicsPROFILE" -l"LowLevelParticlesPROFILE" -l"PhysX3PROFILE" -l"PhysX3CommonPROFILE" -l"PhysX3ExtensionsPROFILE" -l"SceneQueryPROFILE" -l"SimulationControllerPROFILE" -l"PxFoundationPROFILE" -l"PxTaskPROFILE" -l"PxPvdSDKPROFILE" -l"PsFastXmlPROFILE" -l"PhysX3VehiclePROFILE" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/mtlpp/mtlpp-master-7efad47/lib/IOS/libmtlpp.a" -l"z" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/PLCrashReporter/plcrashreporter-master-5ae3b0a/IOS/Release/libCrashReporter-iphoneos.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/ICU/icu4c-53_1/IOS/lib/libicudata.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/ICU/icu4c-53_1/IOS/lib/libicuuc.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/ICU/icu4c-53_1/IOS/lib/libicui18n.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/ICU/icu4c-53_1/IOS/lib/libicule.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/ICU/icu4c-53_1/IOS/lib/libiculx.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/ICU/icu4c-53_1/IOS/lib/libicuio.a" -l"freetype2412" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/HarfBuzz/harfbuzz-1.2.4/IOS/libharfbuzz.a" -l"png152" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/OpenSSL/1_0_1s/lib/IOS/libssl.a" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/UE_4.20/Engine/Source/ThirdParty/OpenSSL/1_0_1s/lib/IOS/libcrypto.a" -l"PhysX3CookingPROFILE" @"/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/Build/IOS/LinkFileList_AR_Sturla.tmp" -o "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Binaries/IOS/AR_Sturla"'
ProcessResult.StdOut:   Upload took 00:00:00.4436010
ProcessResult.StdOut:   Execute took 00:00:06.9856312
ProcessResult.StdOut:   [2/3]  B:\Projects\Epic\Projects\AR_Sturla\Binaries\IOS\AR_Sturla
ProcessResult.StdOut:   Doing /usr/bin/xcrun  actool --output-format human-readable-text --notices --warnings --output-partial-info-plist "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/IOS/Resources/assetcatalog_generated_info.plist" --app-icon AppIcon --enable-on-demand-resources YES --target-device iphone --target-device ipad --minimum-deployment-target 9.0 --platform iphoneos --product-type com.apple.product-type.application --compile "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Binaries/IOS/AssetCatalog" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/IOS/Resources/Assets.xcassets"
ProcessResult.StdOut:   Execute took 00:00:04.3237317
ProcessResult.StdOut:   [3/3]   actool --output-format human-readable-text --notices --warnings --output-partial-info-plist "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/IOS/Resources/assetcatalog_generated_info.plist" --app-icon AppIcon --enable-on-demand-resources YES --target-device iphone --target-device ipad --minimum-deployment-target 9.0 --platform iphoneos --product-type com.apple.product-type.application --compile "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Binaries/IOS/AssetCatalog" "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Intermediate/IOS/Resources/Assets.xcassets"
ProcessResult.StdOut:   Doing bash -c 'if [ -e "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Binaries/IOS/AR_Sturla" ]; then eval $(stat -s "/Users/ardev/UE4/Builds/F2770/B/Projects/Epic/Projects/AR_Sturla/Binaries/IOS/AR_Sturla") && echo $st_mtime,$st_size; fi'
ProcessResult.StdOut:   Execute took 00:00:00.2666916
ProcessResult.StdOut:   Total build time: 38,48 seconds (Remote executor: 14,77 seconds)
CommandUtils.Run: Took 38,8964628s to run UnrealBuildTool.exe, ExitCode=5
<>c.<PrintExceptionInfo>b__4_1: ==============================================================================
<>c.<PrintExceptionInfo>b__4_0: ERROR: UnrealBuildTool failed. See log for more details. (C:\Users\joi\AppData\Roaming\Unreal Engine\AutomationTool\Logs\B+Projects+Epic+UE_4.20\UBT-AR_Sturla-IOS-Development_2.txt)
<>c.<PrintExceptionInfo>b__4_0:        (see C:\Users\joi\AppData\Roaming\Unreal Engine\AutomationTool\Logs\B+Projects+Epic+UE_4.20\Log.txt for full exception trace)

Notice how None of the actual commands actually fails, yet UnrealBuildTool exits with code == 5.
(the UnrealBuildTool log file also shows no errors).

Also note how the text after [2/3] and [3/3] appears to make no sense. Is it possible that the UnrealBuildTool has some problem performing these kinds of actions?