My happiness rating for some survivors have become to 10% for no reason. I checked to see what was the problem by tapping one of the Dwellers who had low happiness rating. He was not injured or anything so I didn't understand at all. Until one of them said "Oh a Corpse!" I checked the water plant but there was not even a body, BUT I think it may have bugged from previous dead corpses, so now, a dead corpse that isn't even on the premises of the plant, is there forever until I destroy the whole thing. But I don't want to because its max upgrade... So what to do...