I had a problem with the HR scores of my XC Ski Classic activities for the whole winter. The score varied between 89 and 120bpm for a 1h training at my highest capacity almost every time (did that about 12 times). When I used the hiking app while skiing at the end of the winter I was able to have more reliable data. For the same training I was between 167 and 185bpm. Is the problem my watch or the app?