On my Watch4 I only see the VO2 max when I manually start a workout on my watch, not auto-detect. You also have to have GPS turned on I believe, and there are some other criteria for it to register and display which I can't remember or find right now. Looking online, might have to do at least a 20 minute workout. I walk fast (where autodetect thinks I'm running slowly) so it works for me on my walks. Otherwise sounds like it just applies to running. I did get a measurement on a walk that was only 18 minutes so not sure about the 20 minute guideline. Again, the big determiner is manually starting my walk.
And now today after my walk I didn't get the VO2 Max information. Instead it gave me today's weather. Not sure why since every other aspect of my walking workout was the same.
