Stuck Inventory Folders Work-Around
It can happen, at times, that single items, or one or more folders of items, get placed below the standard main folders: My Inventory and Library. Attempts to move or delete these items/folders result in a crash. This is a known server issue which goes back a few years at least.
Firestorm brings a way to repair this. Right click on the folder and you should find an entry “Move to Lost & Found”. Click that, and the folder will be moved to your Lost And Found folder. From there, you may drag it to where it belongs.