Logs filled with these messages below, and new tracks never play, only vanilla ones.

Tried to play a track from the theme, but none were appropriate right now. This theme requires more tracks.

Root level exception in Update(): System.NullReferenceException: Object reference not set to an instance of an object
at RimWorld.MusicManagerPlay.StartNewSong () [0x0000c] in <95de19971c5d40878d8742747904cdcd>:0
at (wrapper dynamic-method) RimWorld.MusicManagerPlay.RimWorld.MusicManagerPlay.MusicUpdate_Patch1(RimWorld.MusicManagerPlay)
at Verse.Root_Play.Update () [0x00037] in <95de19971c5d40878d8742747904cdcd>:0
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.Root_Play:Update ()



Edit: Fixed by choosing a theme through the mod settings, duh.