Music discs reverting to original name after being played, even if they've been renamed by the anvil

When the anvil was introduced, I tried to rename my music disc to an alternative name to match the song played by it.

I went to the anvil and renamed it and everything worked perfectly.

But when I played the disc and then ejected it, the ejected disc no longer had my custom name, it was just named "mall" again.

steps to reproduce:
1. obtain a music disc
2. rename it using the anvil
3. insert into a jukebox
4. eject disc from jukebox
5. the ejected disc will no longer carry the custom name

Here is an album showing what I just explained: https://imgur.com/a/BLHFm