Item frames disappearing without any known reason

I had roughly 100 item frames on chests, not trapped, but regular chests in my chestroom. These chests intersect with 6 different chunks at varying levels of occupancy. Every single item frame has disappeared. there are no mob farms, no change to the entity cramming rule from how mojang sent out the pre release, no damage to the structure, no lighting, no mob explosions, nothing. they all simply disapeared.