On a related note, although that to-be-shared folder is not even accepted, let alone has started to sync on the local PC named “HAF…”, it shows up as “Syncing” with HAF on the remote PC:
This confuses me. Is that how it is supposed to look like?
The screenshot hides the important parts: Is the ignored, unshared folder listed in the “Folders” row? If yes then it can’t in fact be ignored and unshared. If it really is, please provide a screenshot also showing the folders to confirm and get context.
It’s not unshared (anymore?). There might be something wrong for you with that, in which case you should unshare, but the info displayed is consistent so I don’t see a problem from Syncthing’s side.
Unexpected folder “…ordner von PC…” [Folder ID] sent from device [PC… Device ID]; ensure that the folder exists and that this device is selected under “Share With” in the folder configuration.
Yes, this is expected. You’ve shared a folder with someone, and they haven’t synced it yet so we consider them less than 100% in sync and offer the optimistic assumption that they are probably working on it (“syncing”).
On a general note: I might have been a bit slow here to grasp what was going on, however it would have helped a lot if you didn’t release the information by pieces: Post full screenshots (like you did in your last screenshot) and describe everything that you hide and might be relevant.