Map will not show in item frame

I can also confirm that this occurs in both singleplayer and multiplayer worlds, in any game mode, running 14w04b. The item frame will grow to fit the block it is placed on, but the map itself does not render.

Maybe it's because of the weird way that entities render before blocks, and something weird happens in the rendering, and since there are no blocks when rendered, they realize this and pop off. But, why has this never happened before?

Confirmed. Due to bug MC-45826, all item frames popped off the wall when an older world was updated to 14w04b. When I attempted to replace the maps, the item frames enlarged but the maps were not displayed.

@Kieren

I do not agree its just older worlds. I created a brand new world in 14w04b and then created a new empty map. I then moved around some so that part of the map was explored. I then put the map in the frame and it added to it. I got the green background on the frame and the map was out of my inventory. HOWEVER, it rendered nothing. Even though part of the map was explored.