This calibration does not work at all. The altimeter (at least on the Vivoactive 3) is complete garbage and does not work, and Garmin just won't admit it. In my case, it is always, always, always, several…
This doesn't seem to work for a number of people for the VA3 as shown by this thread. There seems to be an issue with either the device hardware, software or the design of the ports on the underside…
OsiMik, are you getting yours replaced? Keep us updated if you do and if the elevation issue is fixed in the new device. I got my device in Nov 2017 and have always had issues with elevation. My buddy bought a VA3 in August of 2018 and he has the same issue. I got a replacement unit in ~May-June of 2018 and had the same elevation issue. Replacement unit did have better battery life so wasn't totally a waste. Got tired of dealing with this issue, especially since it was such an easy workaround to use elevation correction in Garmin Connect and Strava.
BTW, Garmin support sometimes monitors this forum. Usually right after a firmware update for a few days and then silence.
I own the Vivoactive for about a year now and riding mountain bikes.
Following the procedure doesn't help and the accumulated height measurements is really bad.
It is about 40% off comparing to Strava on the phone.
It always shows me as if my house, when returning from a round trip ride, is ~70m or more lower than it was when I exited it to the ride.
It was once replaced due to this issue with no help. always on the latest SW update.