Total Ascent and Descent No Longer Match

I've only seen errors like that when a weather front passes through.

Same here, my 530 is consistently very accurate on elevation.  My most recent mtb ride was 1942 feet ascent, 1932 feet descent.

+1 on the tether!  I don't know why you wouldn't use it, takes just a second to pass the unit through the loop around the bars. 

I seem fortunate that I have one of the better 530s out there.  If the 840 wasn't reporting so many issues on the forum I'd be tempted, but my 530 works too good to consider replacing with something that's questionable.

The 840 screen isn't any better, so I'll wait.  Hopefully when an 850 arrives, it's worked out by then.  A better screen and touch with buttons is all that I'm really interested in.  Slightly larger screen would be nice too, but not huge.

Earlier on in this thread, I posted the following "Basically, I give up, the 530 has a mind of its own regarding elevation. Perhaps, Garmin would have done better if you could set the elevation manually like an aircrafts altimeter with just a simple display and a "+" and a "-" option to increase or decrease it.

Well yesterday, I found out that on the Edge 530, you can set the elevation manually before a ride, how it has eluded me I don't know, maybe I have seen it, but forgot about it with getting "Brain fog" with covid, and why nobody else who read my comment did not also respond by saying "You can do it manually" to me suggests the majority of people do not know about this tucked away option.. No doubt everybody will be saying they knew, but if you did, why did you not respond!!!! So basically, you never knew.

To find the option, when you start the 530, you select your activity profile, which takes you to your first data page, then you press the "top right button" again which opens up a menu, (I always do this anyway to select my course, but that is far as I ever go on this menu page unless I change some settings etc), and once this menu is open, scroll to the bottom and there is a "Set elevation" option.

Open it up and just enter what the known elevation is for the spot where you are. I tried it, and sure enough, there is no calibrating elevation etc message when you press "Start" and the elevation that you entered is showing in the elevation data field.. Due to the inclement weather at the moment though, I have to test it out on the road, maybe next Monday when it warms up and snow and ice clears.

Also I saw that the elevation data has an accuracy of + or - 10 metres which I have known about but never took into account, so basically, that also could affect the overall difference between Acended and Descended. For example, you would only have to climb or go down a few hills and have a +/-10 metre discrepancy and it would make a big difference along with any changes in atmoshperic pressure.

Oh well, despite finding out how to use the "Set elevation" option, and it worked, I am now finding, it does not work 

This morning, after 5 attempts to try and get it to work, each time I set my elevation to the spot I was stood on, the 530 would change it to something else, so I gave up with it.

Without doubt, Garmin Edges are useless, every release of the new models are bugged and the old ones are never sorted of their bugs. Garmin might as well just randomise readouts for speed, cadence heart rate power fields etc and then it will match all the other rubbish that gets displayed on the data pages.

Create a custom location where you normally start your rides.  Edit the location to enter the elevation for that location.  Now every time you start a ride at that location the unit will automatically set the elevation to whatever it is in the saved location.

As I have mentioned earlier in a posting, this does not happen. I have a custom location of next to my front door saved including the elevation. When I press "Start" it flashes up "Calibrating Elevation........" but what shows up in the "Elevation datafield" is not the elevation that I have stored for my custom location, it can be as much as 50' to 150' different + or -. 

And as I only have that one custom location saved, it cannot be getting confused with any other. I have even deleted it and made another to replace it, makes no difference. Even resets do not resolve the issue. And I have just been outside with the 530 and my old 800, stood on the location which is saved with a 66' elevation, the 530 displays 78' and the 800 66' as it should.

Is it possible you're starting too soon after a GPS fix (or even before a GPS fix)? I turn on my 530 as soon as I arrive at a trailhead, before getting ready to ride, which can be 10 or more minutes before setting off. When I press Start, my 530 says "Elevation Point Found"

No, going back years, since I had a 305 and an 800, soon as I get up and at least a minimum of 15 minutes prior to riding, I turn my 530 on to get a good GPS lock and for it to stabilse itself. I read to do this many years ago. These days, its at least an hour before riding. Also, I notice on the map, I am exactly where I am on it and confirmed with the location icon right next to my house at my front door and on the "riders triangle"

But, I have never ever seen that message "Elevation Point Found" before, only "location calibrating......". Plus, I can find no reference anywhere in any Garmin forum being reported by anyone of that message popping up. The only time I see a "Named" location is when I get to one and its name pops up on the display.