Missing users after update


Maybe someone can help me.
I installed nextcloud 12 and created users and so on. All was working well until i upgraded it to version 13 via Console.

Now i can still log in as admin but no user can log in.
When logged in as Admin, i can not see anything under users. I tried to manage users, but the right pane is completely empty. On the left i can see groups and how many users are in them but right pane still empty.

Any ideas how to fix that?

Thank you