On my fr735xt, the built in heading data field works correctly when GPS is off or I'm not moving, but the info.currentHeading does not, it requires GPS.
Ok, I tried this on a 230 (indoor running so no GPS and no HW compass), and "heading" bounces between S and SE, regardless of which way I'm going. While's it displays a heading, it's bogus. It probably should display "--" or something, as it needs GPS to figure out your heading.
Same test on a va-hr (indoor walking) and it shows a real heading in the native DF (the va-hr has a HW compass, unlike the 230).
From all the specs I've seen, the 735 doesn't have a HW compass, and should be like the 230 - bad data with no GPS.
I just posted in your thread about this in the 735 forum.
You might want to try sideloading the AccelMag sample in the SDK, as that will use the HW compass if available. It sounds like the 735 might have one..
In one of the recent fr735xt firmware upgrades (4.20 or 4.30) Garmin updated the heading data field (Activity.info.currentHeading) to use the magnetic compass (as well as GPS).
