Incorrect Total Ascent on Garmin Edge 820 after latest update

Do you upload to Strava? Then you can use 'correct elevation', on desktop website Strava, under elevation. It will fix it, my 820 also fluxuates. And check th IQ Connect store for apps for grade / elevation and similar, they can work better than some stock Garmin options. I just put on GRADE DATA FIELD, cause Garmin sais 0% when climbing 14% :)

"Correct elevation" in Strava is not the solution. That is not properly calculated either, usually resulting in a much higher total ascent than real.
There's definitely a problem with the latest update. I have 5000km on my Garmin and never had this problem until now.

I'm not sure if the latest update is the cause. I've stayed on FW 11.0 although I received notifications about 11.2 and I've noticed the same problem from last Thursday on. My ride - the lowest altitude was 315m, the highest 800m which is accurate, however total ascent was only 396m, total descent 550m (one small descent during climbing so total descent is basically spot on). So there is around 150m of climbing missing on a 20km ride... I remember that this or similar problem was present when they launched Edge 820 (+back in the early days there was also an altitude drift - the same elevation point was lower and lower if you did multiple laps of the same track). So it really makes you wonder how issue that was once solved becomes a problem again. Additionally, what caused it is a puzzle because I haven't made any upgrades. S

Installed 11.10 back on it (rollback) and now the Total Ascent seems fine. Definitely something with 11.20

I have note similar behavior( Edge 820 SW 11.20): calculated elevation gain and elevation  loss at least 100 m off. Minimum elevation during  a ride today 1669m, max elevation 2557m (elevation data from the Edge 820). Elevation gain should be at least 888m (small descent in the climb, so I expect at least 10 m more). The Edge 820 reports 779 m elevation gain and 784 m elevation loss.  This looks like a software bug, the math isn't done right.

Alin.Barla - Can you share activity links to the activities with 11.20 and rollback to 11.10?

Yesterday I did the same ride. Elevation and altitude were spot on. I didn't do anything, stayed on FW 11.0 where I had previously wrong data. So, in my case an incorrect elevation occured under 11.0 and it misteriously dissappeared under the same FW version a couple of days later. The good news is that it works - for now . The bad news is that it's difficult to attribute the mistake to FW11.2. If that were the case I wouldn't have an issue a week ago.

I have exactly the same problem. Regular rides on my Edge 820 now have a lower total ascent than used to be, and also lower than my son's Garmin Edge 1030. I record at most half of his total altitude gain. In the Netherlands we have many small climbs and descends, which will probably not help as well. 

Do you by small chance have your Garmin set up for "miles" instead of Km? may be worth double checking.

yeah, total ascent is pretty much crap on 11.2.  I rode 54 mile in North Georgia today... My Edge 820 running 11.2 showed 5,443 (ft) of elevation gained.  My buddies Wahoo Element showed 6,201 ft.  Thats a pretty big difference!  Not saying his is correct, or mine is wrong, so I logged into Garmin Connect and enabled Elevations Corrected... It adjusted the elevation gained to 6,852 ft?!  I did it as well on Strava, and now it shows 5,904 ft. 

So my elevation gained for today's ride is somewhere between 6852 and 5443?!  With my Edge showing the absolute low end of the range.  I know there are varying things that can affect the elevation calculations, temp, air pressure, etc. but these variances are crazy...