Hi, I found this thread and as I have similar problems with my fenix 5S, I'm writing here.
Probaly someone has additional information or (hopefully) Garmin will make a modification for calculating.
Past months, I used a "Walking" activity of my fenix, made some modifications inside the activity and used it for "Hiking". VO2 max had been calculated and became better and better. So far so good...
But, after having made a connection to komoot, I noticed, that these activities are imported in komoot as activity "Nordic-Walking". I don't like it. Thats why, I took a "Hiking" activity of my fenix and modified for my personal interests. Now, these activities are imported correctly to komoot as "Hiking". Very good.
BUT: Now, VO2 max hasn't been calculated since this modification.
Why can't Garmin calculate VO2 max also in "Hiking". I can't understand... HR+Distance+Elevation and other values are cumulated exactly identically...
It maked no sense to go back to a walking activity, as I always have to swich in komoot manually.