Update on this: I just noticed the "Preferred audio driver" setting, and I set it to "ALSA" and audio now works as I'd expect. Probably still worth investigating why the default didn't pick the correct one for my system, but at least my game works correctly now

If some other program is making sound (e.g. I'm watching a youtube video) when I start the game, then it doesn't play any audio (neither music nor sound effects). Once the other audio source stops (e.g. I pause the youtube video), then it suddenly plays all the sound effects that should have played ...