I'm playing on PC, and ever since I have added cdlc to my game, I will play a few songs (at normal volume) and then all songs will start getting very quiet, however the guitar or bass will stay at the normal volume, meaning I can barely hear the original track at all.

 

This happens for both cdlc as well as regular dlc/in-game songs and so far the only solution I've found is to quit the game and re-open it, but then the volume problems will happen again after playing a few songs.

 

Is this a common problem? Any known fixes?

The trick is to let select a song and start it. Then press "escape" and wait about 3-4 seconds, without making any noise with your instrument, then "escape" back into the song, and the volume goes back to normal.