FR255 Altimeter flatlines during runs only - works great for other activities

I went on a short run yesterday and today. Both times, the altimeter data had the correct starting value but it didn’t change at all during the run, when there should have been at least 50 ft difference from high to low.

strangely, it works great for biking and walking on the same roads. Today my run was immediately after a bike ride, and the ride worked and the run didn’t.

seems like the issue could have coincided with the latest firmware update but I wasn’t paying close enough attention to be sure.

Sensor port is clear. Altimeter and Barometer both set to default auto settings I’m at a loss!

Anyone else having this issue?

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0 zappadaa 2 months ago

Similar issue here; the recorded elevation in the fit file is completely flat, even though the elevation shown during the workout is correct. This is with Bike profile, I assume the sport type does not affect to this. And now and then also the recorded elevation works fine. The problem started with a recent SW update.

0 8735557 1 month ago in reply to zappadaa

Vivo en un segundo y hay momentos me marca 5 otras veces 8 y hasta 11, la verdad que no lo entiendo estando todo en la misma planta.

0 Daniel 1 month ago

FR255, fw 20.29: the same issue, just slightly modified - in some running activities it works as it should but from time to time an activity shows no elevation and flat profile, as you described. I haven't found yet what it might have to do with...

0 4679615 1 month ago

Problem still persist even in fw 20.31

It is not in every run, but in 1 of 3 there is still 0 meter gain, completly flat,
connect.garmin.com/.../17240753562

0 Daniel 1 month ago in reply to 4679615

in FW 20.32 issue persists on - exactly as written here, ca. 1 of 3 act. is flat.

I have also discovered - during activity, using data screen with a GPS altitude and a barometric altitude (for comparison), the gps alt. is working while the barometric alt. keeps looking like frozen (no changes at all, the same altitude all the activity). It must be a Garmin bug, hopefully not associated to HW (for example, a defective production batch with failing barometric sensor?) but SW issue...

0 hlbnet 24 days ago

Same. 1 run out of 3-4, no altitude change is recorded.

0 zappadaa 15 days ago in reply to hlbnet

The issue seems to be related to the auto-calibration of the barometer, if you start the activity quickly so that the barometer is not calibrated, the result is a flat elevation. I assume the watch uses GPS for the initial altitude, and if the watch does not have the GPS reception when the activity is started, the auto-calibration fails.

0 ovekvam 15 days ago in reply to zappadaa

That could explain why it doesn't happen to me. I always wait for green GPS status before starting the activity.

0 RM 15 days ago in reply to ovekvam

I also fit in this situation. Altitude is being registered as expected on 100% of the activities and I also only start after GPS gets green status...

Either it is or not the reason, it's at least quite easy to confirm!

0 gamio 11 days ago in reply to ovekvam

I am also waiting, but the altitude is always overestimated at the start. And even if the start and finish are in the same place, the height is much higher at the start.