Fortunately I discovered the problem and yes it was simple. The “MIDI Thru Active” button in Cubase > Preferences > MIDI was unchecked. I don’t remember ever disabling it but in any case, problem solved! 
Fortunately I discovered the problem and yes it was simple. The “MIDI Thru Active” button in Cubase > Preferences > MIDI was unchecked. I don’t remember ever disabling it but in any case, problem solved!