I’m having a problem with FMOD 2.01.09 integrated with UE 4.26, as active voices drop down heavily with no additional issue being showed by CPU or any other event instance. This results in audio stutter.
What could cause such a drastic drop?
Is your game playing more than one or two streaming assets at a time? Playing streams require constant disk I/O, so most drives only support a single-digit number of streams; attempting to play more than a very small number of streams at a time is likely to result in the kind of stuttering and low apparent voice count that you describe.
Assets set to stream are marked as such in FMOD Studio’s Assets Browser. Change them to not stream, rebuild you banks, and see if that improve your game’s behavior.