Windows client doesn't "see" folders on servers


I run a desktop client that syncs to three accounts on three different server instances. With all accounts I ran into the same problem a few weeks ago: On the account’s tabs the entire folder tree (except the Nextcloud Talk folder, if present) went missing while the local files/folders are still present (yet marked yellow for being out of sync):

Directory tree pane in the desktop client:

Local files/folders in Windows explorer (still matching my directory structure on the nectcloud server, but out of sync):

The problem came up at the same time for all three accounts on that specific windows client for that specific windows user. Mobile clients and other windows users on the same windows machine aren’t affected, even when they access the same account on the nextcloud server. I was hoping that client/server-upgrades will fix it, but that lazy way didn’t work out. The client/server logs don’t show any errors that could explain what actually happens here. So this seems to be a matter of my windows client configuration.

What am I missing here?

Nextcloud server versions are 24.0.3 and 24.0.4 (all affected)
Windows client version is 3.6.0 (the issue occured with 3.4.x for the first time, update to 3.6 didn’t help)
Windows version is 10.0.22621