After generating proxy meshes, and then after editing the cluster, ie. removing or moving items, and upon renewed generate proxy mesh initiation, the editor crashes (see log below). The correct behavior would be a warning message and abortion of generate proxy mesh task.
FIX: Delete clusters, Create Clusters, Genrate Proxy Meshes.
[2016.12.27-17.57.00:156][298]MapCheck: Info Map check complete: 0 Error(s), 0 Warning(s), took 543.969ms to complete.
[2016.12.27-17.57.00:157][298]LogFileHelpers: Loading map 'LowLands' took 63.122
[2016.12.27-17.58.23:367][496]LogStats: STAT_HLOD_InitializeClusters - 1.100 ms
[2016.12.27-17.58.23:368][496]LogStats: STAT_HLOD_FindMST - 0.011 ms
[2016.12.27-17.58.23:737][496]LogStats: HLOD_MergeClusters - 365.787 ms
[2016.12.27-17.58.23:755][496]LogStats: HLOD_BuildActors - 17.962 ms
[2016.12.27-17.58.23:762][496]LogStats: STAT_HLOD_InitializeClusters - 0.223 ms
[2016.12.27-17.58.23:763][496]LogStats: STAT_HLOD_FindMST - 0.014 ms
[2016.12.27-17.58.24:202][496]LogStats: HLOD_MergeClusters - 436.296 ms
[2016.12.27-17.58.24:220][496]LogStats: HLOD_BuildActors - 18.723 ms
[2016.12.27-17.58.24:228][496]LogStats: STAT_HLOD_InitializeClusters - 0.080 ms
[2016.12.27-17.58.24:229][496]LogStats: STAT_HLOD_FindMST - 0.001 ms
[2016.12.27-17.58.24:257][496]LogStats: HLOD_MergeClusters - 25.263 ms
[2016.12.27-17.58.24:269][496]LogStats: HLOD_BuildActors - 11.883 ms
[2016.12.27-17.58.24:275][496]LogStats: STAT_HLOD_InitializeClusters - 0.047 ms
[2016.12.27-17.58.24:276][496]LogStats: STAT_HLOD_FindMST - 0.001 ms
[2016.12.27-17.58.24:288][496]LogStats: HLOD_MergeClusters - 9.272 ms
[2016.12.27-17.58.24:297][496]LogStats: HLOD_BuildActors - 8.648 ms
[2016.12.27-17.58.24:297][496]LogStats: STAT_HLOD_BuildClusters - 1006.831 ms
[2016.12.27-17.58.24:298][496]LogUObjectArray:Warning: Invalid object index -572662307
[2016.12.27-17.58.24:305][496]LogWindows: Windows GetLastError: The operation completed successfully. (0)
[2016.12.27-17.58.24:550][496]LogCrashTracker:
[2016.12.27-17.58.24:550][496]LogCrashTracker:
[2016.12.27-17.58.24:550][496]LogWindows:Error: === Critical error: ===
[2016.12.27-17.58.24:550][496]LogWindows:Error:
[2016.12.27-17.58.24:550][496]LogWindows:Error: Assertion failed: Actor->IsValidLowLevel() [File:D:\Build\++UE4+Release-4.14+Compile\Sync\Engine\Source\Editor\HierarchicalLODOutliner\Private\HLODOutliner.cpp] [Line: 1261]
[2016.12.27-17.58.24:550][496]LogWindows:Error: Invalid LODActor found in ActorArray
[2016.12.27-17.58.24:550][496]LogWindows:Error:
[2016.12.27-17.58.24:550][496]LogWindows:Error: