I just did a really hard Zwift race, imported the activity from Strava.
Keept the watch on and used it as hr in zwift.
It was a 50 min full gas race and my hearth rate was in the highest zone the entire time.
Now all i get for it is 10 low intensity minutes, this is not right.
My activity scale is 4 and hr zones and max hr are correct.
Here is a screenshot of the activity and the minutes