I’m certain it doesn’t happen in 4.12.5. We’ve been with that version for a while and was fine, certainly appears when we moved up from that version.
I just tested with the sound not running in its own thread, edited BaseEditor.ini
[Audio]
MaxChannels=32
CommonAudioPoolSize=0
UnfocusedVolumeMultiplier=0.0
UseAudioThread=false
EnableAudioMixer=false
and it does the same, so its not related to that. Not sure if this ini edit actually matter when we run in editor but it seems it has no impact on the error if it does.