EDIT: This is solved; it was due to my soundfont settings (see below). Not a bug!
I'm having occasional problems with music and ambient sound triggering. Sometimes I'll only hear ambient sounds, sometimes I won't hear either. The main menu music always works though, and sound effects are fine. For example, I just finished the first major quest in Aloria, and after the ending cutscene and dialogs, there was only ambient sound playing. I tried saving, quitting to the menu, and restoring the save, and this caused even the ambient sound to cut out, so the game was silent except for sound effects. Restarting the game didn't' help, I had to reboot my machine and start over to get the music and ambient sound back. Possibly related: the first time I launch the game after booting my machine it hangs, and I have to kill it in task manager. After that it starts normally every time I launch it.
The sound issues may be related to the fact that I'm using a soundfont via VirtualMIDISynth to improve the music. I already had this installed so I figured I'd go for it, and it sounds fantastic when it's working, so I'd rather not disable it.The sound issues are not game-breaking since I can restore sound with some fiddling and reboots. But if there's a better solution I'd love to hear it!
Also, I'm enjoying the game a lot so far!
EDIT: OK, the hanging on first launch thing isn't actually true, it just takes a really long time to load for some reason. I had music this time no problem, but it cut out again when leaving Aloria to the north for the first time. Saving and re-loading the save brought it back without needing to exit the game. Not sure why / when the triggers work or not.
EDIT 2: Behavior seems more consistent now. I'll have music, and it will change to a new track when entering certain places, but when leaving those places and entering the outdoors again there will be no music. Exiting to the main menu and re-loading a save fixes it. Not sure if this behavior is caused by using VirtualMIDISynth with a soundfont or not. But, it's not too hard to fix, so I'll keep playing for now.
EDIT 3: SOLVED! Turns out all the audio problems (and the long load times) were due to a setting in VirtualMIDISynth. It was set to load the entire soundfont into memory before running the game, but my soundfont is large (~2 GB) so this caused issues with audio playback. I turned that setting off and now all the music plays properly and it still sounds fantastic!