The on-screen keyboard filtered this key command


if you get it you can’t edit until you close the on-screen keyboard.
Even it happens accidentally .
go to: Studio—>on-screen keyboard or Alt+k

well… what are you trying to say?

Yeah, the on-screen is going to intercept any key strokes in it’s range while it’s open.
Also, this:
https://steinberg.help/nuendo/v10/en/cubase_nuendo/topics/virtual_keyboard/virtual_keyboard_about_c.html