Altitude way off

I'm enjoying this 945 from its altitude accuracy!

In the settings, I use Automatic Calibration, constantly while in activity, based on DEM.

I actually had a similar problem but mine went down by a lot. Started before an activity at 380 and saw 140 a few hours later - recalibrated using DEM to 387. Very weird. 

Just more data...yesterday went on a 2 hour run, afterwards watched showed altitude as 297ft (actual is 303).  24 hours later altitude reading is 386ft.

I've made a couple of activities to see if the problem persisted with SW version 2.70 and GPS 2.50.

I went for a walk and made an activity on the way there (link). After a good start with the altitude being spot on it drifted to an offset of about +65 m.

On the way back I made another activity (link) and the altitude stayed spot on all the way to the end of the activity, which was a first. The only difference was that I calibrated the altimeter "using GPS" manually at the start of the activity, don't know why as it was already showing the correct altitude, just wanted to try if it made a difference.

I thought I was onto something with that manual calibration using GPS at the beginning of an activity so I decided to try repeating the process to see if I got the same results. I went for a run (link), unfortunately the altutude began drifting quite soon after the start. At the beginning it was drifting upwards (up to +30m), I calibrated it using GPS, right after that it switched direction and started drifting downwards (up to -80m). I calibrated it again, than it was quite OK for about half an hour but then started drifting upwards again (up to +95m). You can clearly see the corrections made to the altitude in the altitude graph of the activity.

Until my last activity my suspicions were towards the barometer, but since in the last activity the drifting changed direction with every manual calibration, I don't know what to think.

I loaded the latest beta SW 2.72 today, we'll see if it makes a difference, but I'm not holding my breath...

I started a post in July about the altitude function, and will update here. I’m also finding a bit of a drift (albeit a smaller one than some of you). My runs always end with more ascent than descent, and this becomes more pronounced based on the number of times I stop and start my watch (ie at traffic lights or between track intervals). On elevation graphs one can see a spike down in elevation where i’ve stopped my 945 during a run. On starting it again (in the same location), the altimeter will slowly work back up to the previous elevation, adding in the those meters to my total ascent. Ex: if I run 25x400m on the track and stop my watch between reps, i’ll finish the workout with 60-75m of elevation gain (2.5-3m of extra gain for every time I stopped my watch) and about 5m of descent. I don’t expect it to be 0 m of ascent and descent on the track (even though those would be the real numbers), but these numbers suggest something isn’t working quite right. This is consistent, and happened with older software and the newest, and with GPS, GPS+GLONASS, and GPS+ GALILEO. My 935 doesn’t have this issue, and i’ll often wear one watch on each wrist simply because my 945 isn’t as accurate. I don’t trust it. Additionally, the tracking isn’t nearly as good nor the accuracy of distance compare to my 935. 

I have had a FR 945 for a couple of months now, and it is almost always consistently off, often double the altitude it should be. How can this problem be fixed ?? Thanks Sue 

Garmin does not and will not recognize this issue. I have 2 garmin 945's and neither can track elevation. Not just off by a little they're nowhere close. Off by 300 to 500 ft every run. It does what it wants. Garbage! I even filed a claim with the BBB after 6 months of getting the run around with garmin reps and management. Mine starts off fine and drifts back and forth through the run. I do start and stop the watch frequently between miles. Ive tried everything. Auto cal and manual/dem/gps. Both 945's do the same. Bad product and module. Fkkn garbage. Done with *** ass garmin!

Which watches do make it better altitude wise???