Network Shares inaccessible (to digikam) after transition to digikam v5.1 (schema v.8)

[digikam-ng.jg at graumannschaft.org]

Hello,

After I managed to upgrade on my debian stable/testing system from digikam 4.* 
to 5.1 (see an earlier post), I now have a new issue: the path definition of my 
network drive stored albums has NOT changed during the database migration, 
however digikam 5.1 is unable to access the images stored on the network - 
when clicking on the thumbnail, the real image is NOT loaded and when trying 
to create a new sub-album/directory in the left album pane (where the network 
stored albums show up just fine), I get a complaint that "file://<path to 
network share missing here>/<parent of the dir to create>" does not exist.

When looking at the corresponding AlbumRoots table using mysql-workbench, I 
get this: https://ibin.co/2wTxwWM8Pitj.png

What's going wrong and how to fix it?

Sincerely, Joh