I have a F7X watch, Edge 1040 and a HRM Pro strap.
When I ride on my bike, I use the HRM strap & Edge 1040 without bringing the Fenix with me (or not wearing it when on trainer).
Most of my activities have intensity minutes and have the HR show up on the daily graph. But like every 1 in 5 doesn't, yet my setup never changes.
Here's one of the activities that synced fine with minutes: https://connect.garmin.com/modern/activity/9957646622 and that is shows HR on a daily graph.
Here's an example of the same setup, but not having Intensity Minutes and showing up on the graph: https://connect.garmin.com/modern/activity/9980169709
and missing from HR graph: 
I consider it a bug - 1040 is supposed to support intensity minutes (and in fact they count just fine on the device), why can't it sync properly every time across all the systems?
