While testing Scummvm 2.5.0 I bumped into this issue too --- seems to be specific as said here to lr-scummvm's interaction with RetroArch as loading titles explicitly with the non-lr version of ScummVm works.

Not sure exactly when this broke, but my RPi3B downstairs works fine on RetroArch 1.8.8 and my 4B on 1.9.7 doesn't work. Tomorrow I'll try to upgrade my 3B to the latest lr-scummvm just to see if it still works, just because I'm curious.

Anyone else hitting this, and have a way to work around without downgrading? Lr-Scummvm is much better for input. It might be tracked here:

https://github.com/libretro/scummvm/issues/183

Just FYI, @mitu gave this tip in another thread:

@clyde This issue seems relevant - https://github.com/raspberrypi/linux/issues/4610. Try using audio_pwm_mode=1 in config.txt and see how it works.

I'll test it as soon as I have the time and leisure to work on my cabinet, but I don't know exactly when that will be.

@mitu I think at this stage a clean reinstall is imminent. Your help and advice is very much appreciated though.