Incorrect Total Ascent on Garmin Edge 820 after latest update

I recently noticed this problem: while the altimeter is working fine, showing the correct altitude, the Total Ascent of the ride is very incorrect. It's adding up much slowly than it is supposed to be, or not adding up at all on some steep sections. At the end of the ride, the Total Ascent is much lower than it is supposed to be.

For example, after climbing from 700 meters to 1700 meters altitude, with some small descents in between, the Total Ascent was obviously supposed to be minimum 1000 meters, but it was only around 600 meters. The Total Ascent for the whole ride was 800 meters, while my friends had 1400-1500 meters (they also have Garmin Edge, 820, 530, probably without the latest update). The same day, another ride with some steep climbs, same problem.

I think it's because of the latest update...

Please fix ASAP, this is totally wrong.