I tried a few more things but ultimately went with an HDMI to USB dongle, in my case I got the el gato as I was tired of fussing. It works seamlessly. I don't know why I could not get the Nikon utility to work anymore, i suspect some sort of permissions thing. Apple has been locking things down more and more.
Now, I am using the Nikon as webcam but i have a piece of art behind me that is high contrast. If I am not dead center of the view, the Z6 switches focus to the art. I have it on Wide Area focus, i might need to tweak the AF settings!!
