I don’t really know when exactly the problem came up, but it has to be in the last few weeks:
Activated groups got synced from the LDAP to Nextcloud, but updated user->group relations didn’t.I decided to solve that problem later until a user contacted me that all shared folders disappeared some days later.
After investigating a little in nextcloud, I found out that all users and groups were there, but all users were removed from their groups.
I started to compare the LDAP settings in Nextcloud with those of a second system and saw that the
Association between Users and Groups parameter in the advanced settings tab was different.
So I changed it from
uniqueMember as shown in the screenshot.
After saving the options, all group associations came back and thus, all folders, too.
I wonder how this change happened. I’m the only administrator of the system and I definitely didn’t change it (otherwise I would remember )