Part of my ceiling was a 3x3 of furnaces. I placed an item frame on the bottom of the one in the middle, I didnt like it, took it off, and both the item and the frame clipped into the furnace in front of it and disappeared. Upon breaking my room apart, I couldn't find my item stuck in any walls anywhere or on the top of the mountain or even the rooms below. This seems to work with anything and not just my enchanted golden apple :,) I've tried reloading the game as well but to no avail.