MIDI information is getting in. I can see the lights, etc indicating that.
The problem appears to be when I instantiate any VST instrument using the Synth Rack explorer. The reason I say that is in the case of Rapid, it's frozen asking for my authorization. If I try, say u-He synths, I get no audio output.
In the same project, I can load up two tracks using both methods mentioned above; one works, the other does not. Not a game changer, just a very odd "bug" that I've never seen before in... 20 years?