Leads Do Not Keep Their Names After Being Attached to a Fence

So I have tried to name a lead with an anvil i used it on a fence and when i picked it back up the name has gone back to lead i have tested it out on my creative world and the bug is in fact real

The bug us really simple to reproduce:

I used an anvil to name the leash

attach it to a fence (i have used oak)

and left click the fence to pick the leash back up