Folder shared with user but is not

I shared a folder to several users and wanted to reverse that.
That worked for all users but one. This one user is still in the list.
I cannot reshare nor un-share that folder with that user.
The user itself doesn’t see my folder anymore. So that is fine.
But according to my view the folder is still shared to that user.
Any action on that user (i.e. “can edit”, “can delete” etc) gives a popup “error while sharing… error”)

Nextcloud version (eg, 16.0.4):
Operating system and version Debian 10:

There is actually nothing in the logs related to that issue.

Can I maybe check the sharing status on the command line?

It sounds like possibly misinformation in the database, but as to how you fix it I’m not quite sure.

Maybe deleting the folder would help?..
But unfortunately this is the biggest folder. not easy to copy that folder beforehand. I will try …