If you create a new layout folder and paste into its naming dialog a folder name longer than 100 characters, the dialog closes and you get an error dialog telling you the name is longer than 100 characters.
But if you try to then edit it to correct the problem, you get a different dialog telling you the layout is in use. But it's not. And it can't be deleted either without seeing the same dialog about it being in use. Which it isn't.
And you have to quit FileMaker and relaunch to delete the folder because it can't be edited and it can't be deleted until you relaunch.