When in creative mode I place down an anvil and try to place a name tag in the first slot (to rename it). The name of the item blinks on the part where items are renamed, and then the item disappears. Works with all items as far as I'm aware (including stacks at a time). could possibly be due to a single repeating command I have that is using the replaceitem command on me, but I'm not sure. I've tried restarting the game and this still happens.

EDIT: Confirmed, that command block looping the following; /replaceitem entity shareyourhead slot.hotbar 0 chorus_fruit ; was causing this to happen.