When I had a world with a lot of progress and changes my name, all my progress just vanished and I didn't even keep my skin.

Steps to reproduce:

1. Create a new survival world with no cheats
2. Exit the world but keep the game on
3. Change your account name
4. Load up back that world

Observed behavior:

Your progress is cleared, and when exiting, it takes forever to save world.

Expected beahvior:

Nothing happens.

Edit: Fixed by logging out and logging back in the launcher, bringing back saved progress. Please close.