User create Folder automatically

Hello to all of you,

in our NC we have a strange Problem. One User has created a Folder shared it for several other People.
Now one of these several People create automatically one folder in the shared Folder. The User could not delete these Folder. The creator of the shared path could delete the Folder but a few Seconds / Minutes later the folder is back.
We also have deleted the NC App on the iPad from the Member who automatically create the Folder.

Any Suggestions who we could solve the Problem?


NC 12.0.3 is installed.