When i Was trying to rename my Elytra Wings in Creative, They dissapeared when i picked them up from the 3rd slot of the anvil when i was done
To reproduce bug:
1.Get a Pair off Elytra wings
2.Get a Anvil
3.Rename the Elytra to anything you want
4.Pick up the Elytra from the 3rd slot
Thats how the bug works
Dupe of MC-91521