22.18 elevation way off

I'm using 22.18 (the Beta) and I haven't noticed anything out of the ordinary on my recent activities.

Is your starting and ending elevation what you would expect?

Is the GPS track what you would expect?

Seems like it's mostly a below sea-level issue which definitely isn't possible around here 

It should be more like this:

But, yes, the GPS track is correct.

Had similar issue. Elevation was off most of the time. Activities with the same start/end would have over 200 meters difference between ascent and descent and even activities on flat courses would show lots of elevation gain. Sitting home, altitude was jumping a lot. All that was happening over several software versions. Contacted Garmin, was bugging them for a while and they sent me a replacement watch. Elevation gain and altitude are spot on!

Elevation has been ALWAYS off since I have FR955 from day 1.

It's because altimeter is influenced from temperature. Here it's winter and when I start a run the altimeter immedeately jumps 50m above actual altitude and then, when the watch cools down, comes to normal altitude. During summer this problem almost disappears. My wife with 965 doesn't have this problem and her altitude is perfect.

Garmin has to improve (or develop?!) the algorithm to correct the influence of temperature to altitude

Really interesting @MZ and @Miky - it's winter here also so it might be temperature related. I went back and looked at my data from last winter, when I had the 945LTE (Garmin kindly upgraded me to a 955 after my 945LTE became unusable after a software update) and don't see any issues. So is it an issue with my particular 955 (based on @MZ's comment)

I am actually surprised that Garmin doesn't use mapping to calculate elevation rather than the barometer/altimeter.

Garmin-Sierra - any thoughts on the best way forward with this?

Yeah, that’s what I have read and experienced. But the replacement model is basically spot on. The previous one was all around the place, in the winter especially 

A quick comparison. On the top a run during summer, on the bottom a run in winter. Same roads, it's a round-track I use for 90% of my trainings, you can see between red lines a single "lap" of 2250m.

The start of both trainings is at 208m, calibrated each time just few seconds before starting the run. You can see that in winter, even after the calibration, at the start the altitude immediately jumps higher of about 30m and it continues to go higher to 252m!!! Even the summer graph is quite inaccurate as you can see...

Real altitudes are about 206m for minimum and 210m for maximum

I am curious if anyone knows how many hardware versions of the 955 there were. When my 945LTE was initially replaced for a 955 it was a v1 and was unusable as soon as I upgraded to the latest software. They then sent me a v2 replacement which has been pretty good until the recent elevation issues (except for several HR issues, but now I am getting OT). So I am wondering if @MZ's initial watch was a v1 and was then sent a v2, or is there actually a v3 that he has that might be working better?

Thank you for sharing. I am not sure if this is beta-related, so I will keep an eye out for other reports as well. 

In the meantime, please see Elevation Accuracy of Outdoor and Fitness Devices. (under Factors Affecting Barometric Altimeter Accuracy). If you believe that none of the factors are related to what you are seeing or there is a possible hardware issue, I recommend contacting Product Support directly. Thank you!