Altimeter issues are wiiiiild.

Mezey said:

I am in the same position as yesterday

Do you have set the sensor mode to "barometer only" for this situation?

Yes i have checked it. Auto Cal is off, and sensor mode are set barometer only.

Thanks for the suggestion.

I suspect something changed with the last software update.

Long story, begins last September with my Fenix 7 suddenly showing gradual altitude changes during sleep (and at other times while I was on the same level). I thought I had damaged the 7 by pool swimming with it, and I was putting a case together for Support. It bothered me that the barometer graph was not correct due to large calbration changes.

And my Fenix 6X did not show this behavior, the altimeter was always stable whenever I was indoors on the same floor and stationary (at a desk or sleeping). As far as I know, being stationary should block changes in ambient pressure from being interpreted as altitude changes.

To compare, around October I wore the 2 watches on the same arm for a week. Clear diference: the 7's altitude was not stable during sleep, and the 6's was stable. 

But after version 26.85 the Fenix 6 shows a comparable altimeter drift. Especially during the first 6 to 12 hours after an activity. Unless the watch is not on my wrist; in that case altitude remains stable. Nightly calibration resets the altitude to a correct level, after that further drift is seen.

Theory: There have been changes to parameters that block altitude changes due to ambient presssure changes while the user is not moving (a lot). The change was introduced on Fenix 7 before it made it to the Fenix 6.

My workaround: yellow notes on the door that remind me to set the altimeter to Auto when I go out, and to Barometer Only when I come in.

Yes i have noticed the same issues on my f6 pro. I have to keep and use it as i have paid for it, but it will be my last fenix watch for sure.

Mezey said:

I have to keep and use it as i have paid for it,

The point is: I have paid for a watch with crap GPS, but that was otherwise fully functional. With the firmware updates 19.xx, 20.xx and 21.xx, respectively, Garmin made unusable

• Altimeter / measurement of height gained in an activity
• RD Pod / running metrics
• Usage of watch faces from Connect IQ
• Swimming metrics for pool swimming

They have been promising fixes for these issues since, with decreasing frequency and credibility, but nothing ever happened regarding these bugs and I'm quite sure that nothing ever will, because Garmin obviously just doesn't care anymore. They have our money, and letting employees work on EOL devices will only minimize shareholder value.

Mezey said:

but it will be my last fenix watch for sure.

Same here. I have been a user of fitness and sports/GPS watches and devices for over 25 years now, and this is - by far - the worst experience that I have ever made in this area, including several other devices from Garmin. I will not reward thisattitude by buying another Garmin device, that's clear.