In the mean time I have time to take care of my loved roon NUC machine.
I did
reinstall the roon OS in the web admin
stop the roon server
emptied the cache via the Windows roon app
the I stopped the NUC
turn it on
Now there running the the same builds on the frontend (Windows notebook) and on the optimized roon optimized core kit and also on my Android smartphone
and the nerving messager, that their should be and update installed and it does not install it is gone