Shalidor's Shrouded Realm bug?

honeybun

In the big underground area of the house, in the north west corner there seems to be stone sticking through the ceiling, and the bottom part of the stone is invisible as well. From what I can tell, I think it is from the built in archway up top. I don't know if this makes a difference, but the only thing I have on the arch way is an AD banner.