I have my Vivoactive 4S set up to track intensity minutes by Heart Rate Zones (3,4). When I look at specific activities and the time in HR zone chart under the charts menu. The times spent in zone 3 and 4 don't add up at all to what the "intensity minute" report generates (Intensity report is much lower and seems to have no relation to the time actually spent in the HR zones). This is based on the rowing app using an external heart rate monitor. No special HR zones for running or cycling configured. There is something just wrong. Also not sure that when setting vigorous to HR zone 4 whether that includes HR zone 5 (it should but it isn't clear). Not the issue here in this case.