Sounds dropping out/not loading

[Derpford]

I've noticed that in certain WADs and PK3s--specifically, those which add lots of new sounds--there's an issue with sounds suddenly going silent.

For instance, I'll be playing ww-nazis.pk3 with Epic2 (because why wouldn't I be playing that?), and suddenly the MP40 will go silent. Or the grenade explosion no longer plays. Or the reloading sound for the trenchgun stops playing. Sounds start disappearing one by one, and I've no idea why.

CORRECTION: I am a dummy. I had music set to 0 volume. Previous issue still stands.