I’m fairly certain this bug was introduced in the 4.18.2 hotfix.
I get a null pointer crash by using the nodes AddMasterSubmixEffect() or ClearMasterSubmixEffects() inside a blueprint.
Don’t really need steps to reproduce, just add the node and make sure it triggers. I’m doing it on RightMouseButton.
ACCESS VIOLATION - code c0000005 (first/second chance not available)
UE4Editor_AudioMixer!Audio::FMixerDevice::AudioRenderThreadCommand() [d:\build++ue4+release-4.18+compile\sync\engine\source\runtime\audiomixer\private\audiomixerdevice.cpp:623]
UE4Editor_AudioMixer!Audio::FMixerDevice::AddMasterSubmixEffect() [d:\build++ue4+release-4.18+compile\sync\engine\source\runtime\audiomixer\private\audiomixerdevice.cpp:577]
UE4Editor_AudioMixer!UAudioMixerBlueprintLibrary::AddMasterSubmixEffect() [d:\build++ue4+release-4.18+compile\sync\engine\source\runtime\audiomixer\private\audiomixerblueprintlibrary.cpp:56]
UE4Editor_AudioMixer!UAudioMixerBlueprintLibrary::execAddMasterSubmixEffect() [d:\build++ue4+release-4.18+compile\sync\engine\source\runtime\audiomixer\public\audiomixerblueprintlibrary.h:14]