Baffled by Cubase 12 VST's not working

All my VST’s work in Cubase 11 (latest ver), but stopped working in Cubase 12 (also latest ver). They used to work fine. Re-install of Cubase 12 didn’t help and no errors present that I can find. My Mac has no errors in the Log files. I can record in MIDI, still without hearing anything and during playback only the MIDI mixer shows any activity but no sound. No VST’s appear to be disabled, either. I can take the same Cubase 12 project and it plays fine on another Cubase 12 computer, but not the main studio computer. Anyone have any ideas? Pulling what’s left of my hair out here!

Is there any activity on the output channel of the VSTs in the mixer?
Which VSTs? All of them? Also if you create a completely blank project and just insert e.g. Halion or Prologue? No other FX plugins in the mixer involved? (we just had a case here where one plugin blocked all audio).
What about plugins in the control room?

No output visible on mixer or control room (not being used-so empty). Old working projects have no sound either. Created a brand new project and recorded one iMIDI instrument with no effects, etc.,but no output…just the MIDI channel showing output. Non-MIDI projects which were all bounced to audio play just fine with all outputs working as expected. It doesn’t matter which company’s plugin’s are used the result is the same. If I open a VST like Kontakt, I can see the MIDI activity light working during record and playback but no sound in either case. I should add that this same new project plays in Cubase 11…

But it’s a Mac.
Search for problems like this related to macOS only, or ask Apple about it.

Well it seem specific to Cubase 12 and nothing else as Cubase 11 and Dorico work fine. Doesn’t seem to me that it’s an Apple problem.

Sounds weird, especially if audio tracks play just fine. Just for the sake of it, have you tried starting with disabled preferences?

One more idea, is by accident constrain delay compensation activated?

Tried disabling preferences but no change. Still no sound. Guess I’ll have to give up on Cubase 12 and go back to Cubase 11.

All right, there seemed to be only one way to get a fresh start with Cubase 12. As I’m sure most Mac users know, just selecting the Cubase 12 App and dragging it to the trash can does NOT delete all the bits and pieces that make up the app. So I used a little app for the Mac called “Find Any File” and searched “Cubase 12” on my primary SSD. and deleted every single reference to Cubase 12 that could be found. Now a fresh install of Cubase 12. So now both Cubase 11 & 12 perform as they should. Many thanks to all who tried to help.