VST Instruments are Inaudible

I have one stereo audio track that I can hear just fine, so I know the audio routing is correctly working. However, I cannot hear my VST rack instruments. The instrument (Cantabile Ivory Piano) is indicating that it is receiving MIDI from the track controlling it, and that MIDI track is registering in the mixer as receiving audio, but I cannot hear it. The Cubase 9.5 manual is not helping me. What can I try?

I get this problem sometimes, but I’ve always found a way out. Can’t remember what it was. I think I simply restarted Cubase, mostly. I once had to recreate/copy a track. Other tracks were working on that occasion.