Hallo Heiner und Team.
Here is some more information, I have a working installation of LMS 7.92 and GMusic plugin vers. 0.60, which I installed earlier from the external repo and not via the „special plugin“ method. Vers. 0.60 remains at this version and doesn’t auto-update. The problem is from a fresh install of M2P/LMS/GMusic, which shows up as vers. 0.70 as the only option. I had a hard time finding the older 0.60 version, using known repos for a manual install.
The working installation is on a RPI3B (Allo DigiOne) and the failing is on a RPI3B+ (Allo Piano 2.1). Unsure if that matters or not.
Gute Arbeit und viele Grüße, -frank