In my case it dropped significantly too. It showed a tremendous drop in my VO2 max from 60 to 49 overnight! And, instead of reporting changes in VO2 max for every workout where I have my HR 140 bpm for an hour or more, now it only shows what it is in the circular and it is not plotted in the historical. This is very frustrating! Because of this, I have to write down in a separate place the most recent Vo2 max every time since it isn't tracked in the history. In my opinion, I prefer the way it was before the update.
