Thanks, I’ve not used a midi monitor before…
In my other Cubase projects I can still play and hear this note using my Korg keyboard (or alternatively) by using the mouse on the Key Editor’s keyboard. So the keyboards(s) are definitely still working in those projects.
But in the latest project when I use the Korg keyboard there is now only input activity, similarly if I use the mouse to play the note on the Key Editor’s keyboard the “piano key” is highlighted but there is no longer any sound.
It seems that something has somehow changed within this particular project’s set up, but I’m not sure what, or why.