I’m in the same boat. When I look under data sources for VO2 Max, there is no sign of my Series 6 watch. Other metrics (heart rate, for example) have it listed. But for some reason the VO2 Max doesn’t recognize the Series 6. I’m going to try to recalibrate and see if that fixes it. But has to be a bug somewhere.
Can you please post an update about it when you have a chance to recalibrate? I tried that with 7.0 and it didn't help, and I haven't tried again with the newer updates.