The bug

Item frames created with /summon (or a couple other ways) seem to be invisible and not truly present. From what I can see, it looks as though their TileX/Y/Z tags are set to zero rather than the position of the frame itself.

This does not happen to paintings, they summon fine and have the appropriate tile tags.

How to reproduce

/summon item_frame
/data get entity @e[type=item_frame,sort=nearest,limit=1] TileX