Thank you for your advice. We used the import functionality only for the first time. Since then we modify the locations manually when necessary.
Now I added the same address (Eberhard-Karls-Universität) as you did. The SLP detected the geocodes as shown in the first attachment. In the second attachment you can see the details of the entry. There the location is shown exactly in the map but the search fails.
Additionally I renewed the geolocation for all locations in Tübingen with no change in the search result.