No sound on playback on Mac M1 (Dorico Pro 3.5)

Have been using for several months without issue. Today my playback stopped working, I am not sure how to diagnose. (This seems unrelated to an earlier issue I reported with Elements.) I have tried rebooting as well as restarting Dorico.

Dorico (1.0 MB)

I looked at this Troubleshooting Playback video and the problem is fixed. Somehow the instrument (piano) was not loaded, and after adding it manually it began working.

I’m still not clear why that is a necessary step, or if it was unrelated to the core issue.