Check that you send Master as the return feed to participants. Point 7 at https://www.vmix.com/help27/ZoomSetup.html

To clarify something, the isolated/mixed audio menu relates to the audio coming FROM Zoom, not the audio going TO Zoom...so that shouldn't be a factor. Otherwise your settings look good to me

vMix 27.0.0.75 x64 does not seem to support Zoom webinars, our Zoom number doesn't show up even after doing a refresh. I checked our settings using your advice but didn't seem to resolve the problem.

The Zoom audio input options do not show something like vMix audio, or vMix Master, or anything else that would include all the inputs in the Master bus. The only thing close is Webcam 1 (NDI Webcam audio).

At this point, I cannot use our microphone audio coming in over NDI from our PTZ camera that is part of our Master audio.

Do you think that the new version, 27.0.0.76 will correct this?

It is possible that vMix Zoom plugin wouldn't work with webinars, as that is a different product than Meetings and behaves a little differently. I would verify that I was able to get vMix's audio into a Zoom Meeting first. Is that working? Like the other user said, you don't go look for the audio output source of the vMix Zoom participant, it just joins and does it's thing. If it's working in a meeting, then I would look at what type of user vMix is coming in as. Zoom Webinars has a different setup where Guests can't unmute or turn video on, but Panelists can. So if vMix joins as a Guest it wouldn't be able to unmute unless you gave it special permission or promoted it to a panelist

I figured it out!

I needed to install a virtual cable to send the master audio to Zoom. The vMix knowledge base describes it: "Send a virtual audio output out of vMix using VB-Cable Virtual Audio Device."

I hope this helps someone else...