Gradient 0%

How does the recorded activity look? Does it have the correct elevation profile, total ascent?

I've actually noticed two scenarios when it doesn't show the gradient (or rather always shows 0%) while riding. Sometimes it at least correctly tracks the elevation and subsequently, the ride in Strave/Komoot later looks correct. Basically, it's "just" an inconvience during the ride. But sometimes (and more often I would say), it then also does not track the elevation and then the later ride entries show 0m elevation. That obviously is more than just an inconvenience.

Just yesterday, I was recording without loading up a route - it worked. It seems to mostly work when freeriding. But when I load up a route (planned in komoot), then it really does not work quite often.

How does the elevation look like in Garmin Connect? Strava I think has an elevation correction. In Garmin it's disabled by default on devices with barometer, but can be enabled in the right side of the web connect, when you look at the activity.

This week I had a ran (with fr965) on my usual terrain and it came up flat. I don't know what happened, especially that both the walks from an back home had correct elevations.

But maybe we're seeing some new bug in Garmin?

I get tracked on a loaded course (GPS is clearly working) and in that situation climbpro kicks in, but at the end of a ride it shows 0 ascent and no elevation change.  Rode yesterday and it was fine, 2 days before, nothing. I’ve reset device and tried every tweak I can find without consistent success

Same here - I just bought an Edge Explore 2, and it worked great for the first few rides. Then I noticed that it's failing to give the gradient reading, which shows permanently as 0% whatever the incline. Weirdly, the 'ascent' reading is working, and when I sync the ride to Strava the elevation gain is fine, so the device 'knows' I'm going uphill. Garmin - we need a patch!! 

Strava does elevation correction. If you go to your activity on the connect website you can enable elevation correction (on the right side below the image of the device)

But true, that Garmin needs to fix this

I had the same problem with mine. Everything worked perfectly fine for the first couple of rides, but then after an update I couldn’t calibrate altimeter manually, by DEM or GPS. I spoke with Garmin support, who advices me to first do a “restart” of the device and if that didn’t work then download the beta update. 

The restart seems to have helped. The restart I performed by connecting the Explore 2 into power and then press the power button for approximately 20 sec - the device will reboot during those 20 sec and the problem is hopefully solved for you as well. 

Btw: The problem occurred two days ago and I fixed it today. 

I would caution about downloading the beta. It usually adds new bugs rather than fixing old bugs. I had many regressions because of beta, that's why I eventually stopped downloading betas. More than once I was told by support to "try" if beta fixes my problem. It never did. Last 2 times I asked if the bug is listed as fixed in the beta's changelog, and surprise surprise: it wasn't. They're just telling people to try beta because they're out if better options, which would be less of a problem if it was like restarting, when they only waste the user's time, but with beta that is not even supposed to fix the bug, they literally just risk to add more bugs and have no chance to fix the existing bug. I guess sometimes there is a fix in the beta for the bug, but always ask if it is the case, and save yourself some time and new bugs if it isn't.