I got Cubase 15 and created an omnivocal track. I dragged a midi track with lyrics and it immediately played.
I went to another project where I had audio vocal harmony. I would have to add the midi notes. I created an omnivocal track and set the input to a piano, have solo on, record and monitor and play keys and nothing registers, To make sure the piano is connected correctly, I take one of the existing midi tracks and set it to the same piano input and get a signal. What does the omnivocal track need?
If I’m understanding what you’re doing, this should work. However, what you’ll hear when monitoring the Omnivocal instrument track while playing it from a MIDI controller is just a sine-type sound. When you play it back afterward, it will just sing “ah” for each note until you enter the lyrics via the key editor.
I discovered that, unlike midi tracks, when you set the monitor to brown (active), any midi entry shows as blue vertical bar, while with the omnivocal track, it doesn’t. But playing keys still records.