Halion Sonic SE 3.4 no libraries found

Hi Experts,
I have been using Halion Sonic SE 3.3 together with Cubase 10.5 Pro for some time. However, after updating to 3.4, HSSE can’t find any instrument sets. Same thing with the Standalone version.
This install procedure gave no errors. The library seems to be fine, sitting at the right place in the Programdata folder.
The library manager finds no libraries. When I click on on the library files, Library Manager indicates the VST Sound is already registered (see attachment)

Things I tried:
Reinstalling Halion Sonic SE 3.4, with or without previously deinstalling with the HSSE installer and/or with Revo uninstaller
Reinstalling Halion Sonic SE 3.3, as above
Reinstalling Cubase 10.5
Countless reboots
Finding a similar problem in the support forum.

Any clues would be most welcomed!

Thanks in advance