Can you post screenshots of the Syncthing Web GUI from all devices?
Also, do you use ignore patterns, and if yes, are all devices connected with each other or not? This is related to the fact that you said in the last sentence that the actual files were synced properly.
I do not use ignore patterns, all are running the defaults, “out of the box”.
All of these devices are active and connected 24/7/365. mostly on my LAN, one via WiFI.
z-620-2SpiralLinux is the New node, and it is having trouble with z620-1-Sid
Hmm, in that case something else must be the culprit. Difficult to say with no errors present in the GUI.
With that amount of data I’d suggest trying to remove and re-add individual problematic folders first and see whether they sync properly or not. You can of course perform a full database reset with https://docs.syncthing.net/users/syncthing.html#cmdoption-reset-database, but this is likely going to be a very expensive operation both in terms of CPU/IO/RAM usage and time.