20.26: No altitude change during activity (recorded wrongly as flat with 0m elevation)

Hi everyone, I've run into a problem with my Garmin Forerunner 955 after updating to firmware 20.26. Yesterday, during a race in hilly terrain, the altimeter got stuck at a single value:

The issue was also visible in the altimeter widget. While it was measuring normally before and after the activity, during the race (where other runners' watches measured about 150m of elevation gain), mine showed a flat line.

I ran the race using the Run profile with PacePro enabled, but navigation turned off.

This seems like a newly introduced bug, as I run often and this is a first time I have seen it, right after updating to 20.26.

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0 Grumpy from dawn till dusk 2 months ago

tomaskafka said:
This seems like a newly introduced bug

No, not in general with 20.26
I have had a long bike ride and a run since updating to 20.26 and the elevation was recorded as expected and showed plausible values.

Have you checked in the "system" - "info" section, if the Sensor Hub has updated or maybe is "0.0.0"?

Also here is a similar discussion:
forums.garmin.com/.../second-run-in-5-days-where-watch-not-recording-elevation-or-temperature-changes

0 tomaskafka 2 months ago in reply to Grumpy from dawn till dusk

There might be more conditions necessary for this to happen, but I want this investigated, as it makes all the data from the run worthless in a hilly terrain, and it ruined a recording for one of my hardest races this year.

Sensor hub version is 31.09, there are no zeros for any of the subsystems.

Thanks for the linked post, it seems like a same issue - I now noticed that the temperature stays flat during the whole 1h40m run which is also highly improbable, so it’s probably a same bug, still unfixed.

0 Grumpy from dawn till dusk 2 months ago in reply to tomaskafka

tomaskafka said:
Sensor hub version is 31.09, there are no zeros for any of the subsystems.

Then it is strange indeed.
Either your altimeter physically died exactly during the update, or there is some bug, that impacts the recording - which obviously applies not under all circumstances.

0 tomaskafka 2 months ago in reply to Grumpy from dawn till dusk

It did not - the altitude widget shows correct data before and after the activity, but during the activity it was flat as well. So, most probably a bug.

0 rptaylor82 2 months ago

I've run into the same problem. No issues at all until the update, now both of my runs since the update have had absolutely zero elevation changes.

0 FlowState 2 months ago

This happened to me with the new update, but only once (today).

It also happened to me a few times 1-2 months ago, so it’s not a new bug for me. There’s no rhyme or reason — one of the affected runs was a workout with hill sprints, right in the middle of a warmup and cooldown that were recorded as separate runs and had normal elevation data.

For another affected run, I went down dozens of flights of stairs before recording the 0-elevation run, and the stairs were counted fine.

0 6106907 2 months ago

This has happened to me on 20.26 as well. I don't think this is just a 955 issue. This is happening to me on the 265

0 thedole 2 months ago

I can't really remember when this issue started for me in relation to when I updated to 20.26, but I have also been having elevation data issues as of late. For me the elevation stays unresponsive until mid run when it suddenly goes normal. Not for every run, but pretty often now.

0 milesnz 2 months ago

First time today Ive done a run with 20.26. I Have the same problem. No elevation change shown at all.

0 Hels_Bells_76 2 months ago

I have the same problem, no issues ever with 965 elevation until the 20.26 update happened - now a flat line!