I can perfectly repro this - imho - erratic behavior.

Regardless of what you enter in the exclude field, the files get scanned anyway AND the sensitivity slider does not stay at “custom” but returns to whatever it was before (either “normal” or “high”).

I have a lot of OpenMG music files on one of my systems and the SonicStage program sometimes has problems playing these files when avast puts itself in the chain.

Maybe one of the avast team members is willing to comment on this.