D5 no sound

I don´t have a sound with Dorico 5. Even if I change the audio driver, it doesn’t help. When I restart Dorico, I get the message “audio engine process died.” What’s going on here?
I`m on Mac OS 10.15.
Some further informations: It seems that Dorico tries to load the Halion 7 library, but my Demo license for Halion 7 Pro is expired. And now Dorico doesn’t load anything, even if I choose Halion Elements in the playback options.

did you restart the Computer?

Yes, I restarted. It didn´t help.

What if you go to the Dorico preferences dialog, on the VST tab, you have chosen HALion as preferred instrument. Change it to HALion Sonic.