If the mod is loaded for the very first time while your save game is already in a tavern, combined with hand painted models + improved interior lighting, the improved interior lighting lights don't load in properly.
To fix, you have to (I believe) is to leave the tavern, save your game, re-load, re-enter the tavern, save inside and then re-load again. I think that was the exact combination required, but I don't remember haha

I guess it's just something about the 3 mods together and fighting over precedence. It seems like it just eventually fixed itself after enough saving back and forth.