Try disabling all mods and figure out which is causing the problem. DId that and fixed the issue. For me, i just had to install a newer version of a music mod I had been using.

In fact, I already did it and the cause is the "!![REP]Music Mod Callback". That's why I made my report and I don't know what you mean by updating it, should it be done on external pages or how?

check you don't have the AB+ version of music callback enabled at the same time, as that can prevent repentance specific tracks (including the main menu music) from playing

as far as updating, basically when a mod is updated steam doesn't always download the new version, sometimes you have to delete it off your computer, or unsubscribe from the mod, run the game, quit and resubscribe, to force steam to get you the latest version