When you try to use a anvil the GUI will only show for a split second then kick you out as if you were to far to open it. (Now there is no way to add enchants to items as we don't have the /enchant command anymore and still don't have the replacement for it)

How to recreate:
1) Update/Open a world from 17w50a in 18w01a
2) Place down anvil
3) Try to use anvil
4) Your done with recreating the bug.

Edit: I found that this bug only happens with world that are updated to 18w01a but if you create the world in 18w01a it wont happen.