The bug
I made a spawner that spawns item frames, and their rotation are random. l also made a painting spawner, but the paintings' rotation aren't random.
How to reproduce
/setblock ~ ~ ~ spawner{SpawnData:{id:"minecraft:item_frame"}}I made a spawner that spawns item frames, and their rotation are random. l also made a painting spawner, but the paintings' rotation aren't random.
/setblock ~ ~ ~ spawner{SpawnData:{id:"minecraft:item_frame"}}(Unassigned)
Confirmed
(Unassigned)
Minecraft 1.12.1, Minecraft 1.13.1, 1.15.2, 20w17a, 1.16.2, 1.16.4, 20w48a
Retrieved
Confirmed this for Minecraft 1.12.1. The item frames seem to be also positioned randomly, and don't take into account where there's a block to attach to. They pop off after a second or so, like item frames always do.
I also noticed that you cannot put any item into the item frame.
This can be used by mapmakers as a method to generate random numbers, though.