Does the true north function work at all? If yes - how?

True and Magnetic North work fine on my Instinct (using latest beta), and they always did. Perhpas the data file containing the recent WMM (World Magnetic Model) is corrupted on your device. Did you already try a master reset of the watch? If you did and it did not help, did you already contact the Support, as suggested by Garmin - Chris in the other thread?

We're talking about release firmware here, so, no, I did not master reset. I honestly don't want to. (I like my settings. Like, a lot. ;) )

Last time I noticed the problem I went back from a beta firmware to 12.20 which to my understanding causes a reset. The problem disappeared. Since the I have not tried out any beta firmware anymore.

The bug is back now, and it has been reported by several users.

Of course there might be misunderstandings here. E.g. Garmin could've mixed up magnetic and true north, so the wrong setting lead to correct readings but false bug reports. Or true north might only work under certain circumstances. (Which still wouldn't explain the 90° offset. Usually, a distinct offset is a clear sign for a programming error.)

Do you know which file contains the WMM? Or what might influence the true north calculation?

As I wrote, I am on the latest beta version v13.81, and both the magnetic and true North are identical, and both pointing to the right direction. And it was always the case with all versions I ever had since 2 years on my Instinct (and I do use to install every beta version available).

So frankly told, I do not quite believe that this is a problem of the latest firmware version. It would have to impact me too. To me it looks more like some data (the WMM) is corrupted, or did not update correctly. The master reset might fix it, but if you are unwilling to test it, we will not know for sure.

8990586 said:

Do you know which file contains the WMM?

No, unfortnatelly I do not know where the WMM table is stored.

8990586 said:

Or what might influence the true north calculation?

Your location. But I beleive you already wrote the GPS was locked and position checked. Then perhaps just the elevation, though theoretically it should not have any influence. But if your altimeter reports the infamous 888888, then there may be indeed a problem with your sensor hub firmware (or its data files), and that might be the culprit.

I am on 13.81 now - magnetic North is fine, verified with GPS compass on a phone, but true North is off 90 deg.

Performed Master Reset as described here - https://support.garmin.com/en-US/?faq=OkQ0pbsjum027l0E0QGR48

Gone through initial setup... Still, true North is off 90 deg.

Actually my true north is off by 130 degrees. If I align my instinct with magnetic direction from my suunto mcg2 it is showing 130 degrees. Also it's almost impossible to perform CALIBRATE function. It was quick and easy previously but now it works once every 10 attempts....
I'm on 13.81.

Mine has a difference of 90 degrees between true and magnetic north, too. I did a soft and hard reset to no avail. I'm on 13.81..

I am now affected by the this, too. The compass became off by 90° all of a sudden. I haven't updated since 13.20 or done anything unusual, it just happened sometime last week and I noticed it yesteday. It is off both in "true" and "grid" mode, but points correctly in "magnetic" mode, so obviously, the sensor is fine.

Has anyone managed to calibrate it properly?

No... just can tell that it was a real problem while setting a grid for an archaeological survey...

I have updated to 13.81beta but still the same issue