Really odd problem, a MIDI keyboard is recognized in preferences and pushes the piano roll keys, but no sound comes out. Clicking on the keys results in a playback sound.
This is on a PC laptop with a docking station. Both the PC and station have a Realtek chip (as do all consumer devices these days incl. Apple). They both register as devices, however I can’t get sound out of the internal speakers, but only the dock, through the low latency driver. And as mentioned only when actually clicking in the lower zone piano, not via MIDI.
I didn’t notice the green light, but the piano roll presses are equivalent so that’s probably the same
By default Noteperformer is chosen, and that was selected and operational for the track on startup.
So it might be the same problem, with the exception that I kicked it in with a default VST
New information …
Now that I had sorted out my audio devices (I set it up to use the low latency with the dock), I exited the application
On loading the project the second time it is now working with MIDI
So if there’s any useful information here, it could be due to first time configuration from perhaps a new installation of Dorico, in that it gets a little confused about the MIDI routing and audio. But once it’s set up and restarted then, with that preset, it correctly works.