My creative world disappeared from my world list overnight. The world file still exists in the saves folder. I was playing on 1.16.3, on Optifine.

What I expected to happen was...:
I was expecting that the world would be there. If I accidentally deleted it, then the file wouldn't be in the saves folder.

What actually happened was...:
I searched through the worlds, but it wasn't in the list.

Steps to Reproduce:
1. Play on your Minecraft world, then log out of the game.
2. Shut your computer down, and turn it on the next day.
3. Look for the world in the game.