Megastrange disappearance of audio thread

Hi everyone,

i am currently fighting with an extremely strange bug which kills the audio thread! First noticed it in Reaper but it is also reproducible reliably in the AudioPluginHost of Juce. In the processBlock is something which consumes around 10% of a core, so it is not that much. I am doing some GUI updates including some file access on the main thread and once i do it, the audio thread is gone. So no more calls to the processBlock() etc.

In the AudioPluginHost i can fix it during runtime by changing the block size for example, in the audio settings. And back is the audio thread and also the processBlock gets called again. Until the update comes again…

Any idea anyone? How can i possibly track that one down? Already one day of stepping through my plugin commenting out and in certain parts, but no clue whatsoever…