I haven't check out the new Betas but I'm a bit surprised that it was changed from Cave/Item Room to Item/Cellar Room.
Did you draw up room 80 correctly? In some of the older versions, you had to do that.
Although, I'm pretty sure what that would never cause the shop to be in the overworld. I'm beginning to think more and more that this is actually a bug and not something that you did wrong.
