Intensity minutes not working properly

I just got a vivoactive3 and since I have it, I've never seen something else than zero, no matter what I'm doing.  It just not working.

Thanks. That may be the root cause. I will try adjusting my class as well to see if that changes things. 

Did this work for you?
I'm having the same issue, recently bought a 1030, to pair with my 945 (when the 1030 went on sale a couple of weeks back), and I've never been more frustrated, with a fitness device.  Both devices have TrueUp enabled, which seems like the "obvious fix" (both were enabled from day1 of config).

Part of the appeal of "adding the 1030" is that I could stop tracking my rides with my 945, and save the battery on it, for walks/hikes/whatever, explicitly NOT tracking my rides on it, instead using the 1030 (both are paired to my HR strap, which handles multi-point Bluetooth without-issue, until now).

Seems crazy to have to start TWO ACTIVITIES, every time, on both devices, surely that can't be the solution (this will be the end of the 1030 "experience for me, it came from a retailer that definitely accepts returns).

Surely Garmin has a device/activity-precedence here, of some sort???

This is such a negative-user experience, IMO, I thought I was adding to my long road-rides, having the maps and all, but the frustration-factor sort of turns that on its' head...

I think you need to make sure activity tracking is turned on in the watch settings. If not intensity tracking seems to stop

I get intensity minutes recorded approximately half the time. Seems every second day I get credit for workouts that definitely are intensity minute worthy. Seems it’s been a problem for a long time. 

same for me on the fenix 6x - went for leisurely treadmill walk - intensity minutes were recorded at 2x assuming vigorous - useless