EDIT: After a bit of f****** around in watch settings, I think I found the issue. Seems that the origin of this is assigned custom HR zones in IM settings :)
I see this topic being discussed as far back as 5 years but without any solution provided from Garmin. Previously I used Forerunner 935, never had issues with Intensity Minute tracking. Several months ago purchased Fenix 7 Solar and 1 or 2 months into using it I noticed that I never reach my IM targets despite having regular running and cycling exercises. For running I use only the watch HR monitor, for cycling Edge 530 + HR strap.
Here's a concrete example of a day with 3:42 hour long running exercise. My average resting HR is 56, so if I understand the IM calculation method correctly, time above 150% of RHR (~84 BMP) should be recorded as IM and time above 200% of RHR (~112 BMP) should be recorded as Vigorous Minutes. I might be wrong about the method how Garmin calculates IM and VM but here's hard data, clearly something is not working as it should with IM or I completely misunderstand the whole concept...
Exhibit #1 - IM status for the day
Exhibit #2 - AVG RHR & day HR pattern including running activity.
Exhibit #3 - detailed HR chart for the running activity
