Model disappeared after adding Location

Running fresh OpenHAB installation (3.0.1) on Synology NAS from docker-image (Docker Hub). Worked perfectly fine for several days. I then added a new location in the model and changed the parent group after saving. Now, my model disappeared. However, the start-page still shows the models’ cards correctly. What can I do to “reset” the semantic model to show up again?
The json file (userdata/jsondb/org.openhab.core.items.Item.json) is filled with all details. Adding a new location added a json entry in this file, removing it removed it. So, this seems to work fine.

Thanks in advance.

Bei mir war das genauso. Meine OpenHAB-Installation läuft auf einem QNAP NAS auch in einem Docker-Image. Gibt es inzwischen eine Lösung für das Problem?

Hi just to log my solution, because it took some time to figure it out.

in org.openhab.core.item.Item.json (in /var/lib/openhab/jsondb) remove the groupname from your top location: