Recently I have had this problem with falling through the top of the stairs all the way down. It dosnt matter if I walk or run, the result is the same. This happends with ALL stairs.
Build 41.78.16, it could be a mod causing this since I havnt had this happend before, but, why would a mod cause this and how? I'm tired of going into debug mode to free my character lol
Think I'll stay away from stairs forever.