The issue is simple: even after hours of playing, I get no music at all. All other sounds (including jukeboxes) are working, except for the ingame music. Moving the sliders did not make the music return and restarting didn't help either. I've not encountered any cave sounds, but that might just be coincidence.
The new furnace sounds for example do work. Tryed starting the game with both no startup arguments and no specific arguments.