I’m finding the way selected pitches are represented on the on-screen piano keyboard a bit unexpected.
Pitches represented by black piano keys not visible. (See screenshot)
After notes are deselected, they remain “played” on piano keyboard. (See screenshot)
It would seem that Dorico can get itself into a state where it will show some but just not show other selected pitches on the piano keyboard (although I can’t illustrate this in the screenshot below, I am pretty sure that this was happening on a large project.)