Glitch 1:
Example: you create a label box that links to a Discord.
Sometimes after moving it around, saving and exiting the editor you'll see one in the new place and one in the old place.

The old one won't show up in the editor so it can't be deleted. If you delete the new one, the old one is still stuck there.
There's no way to remove it in the config file that I can find.

The only way to fix it is to start over. Only seems to happen to external links.

Glitch 2:
Sometimes exiting the editor makes all the vanilla labels (for singleplayer, etc.) appear in their original spots.
Easiest way to replicate this is going into an editor on a loading screen, which really bugs things out.

I wasn't able to reproduce this in a clean instance with FancyMenu + dependencies installed.
It's most probably a mod conflict, so I will close this for now.
Thank you for your report!

Do you use any other mods? If so, please try to start the game with only FM + dependencies installed.

And please include MC version, launcher, used mods and everything from the template. I can’t help you if I don’t know anything about your setup, dude.

full mod list and only on 1.16.5
FancyMenu [Fabric] v2.0.5-1 MC 1.16.3-1.16.5
Konkrete [Fabric] v1.1.7 MC 1.16.3-1.16.5
[1.16.5] Fabric API 0.36.0

blank template, add label, set action to link, put in random link. save layout as. exit.
bug happens once in a blue moon. most of the time its fine.

after making some other changes in fancymenu and later on reloading that file after a game restart, it was gone so it might not be a permanent issue.