While on a realm, anvils:

• sometimes cannot rename an item until an different item has been placed and removed from the second slot
• the renamed item will not appear to have a different name until it is removed from the 3rd slot
• there is a delay between removing the item from the 3rd slot, and it appearing in the inventory. During this delay, chests, crafting tables, the inventory, ect. cannot be opened

 I have a video showing this, but it is larger than 10 mb, so it cannot be attached

here is a link to the video instead: https://imgur.com/a/Xce0x4v