Ever since updating my VA4 to 6.80 I've noticed some major errors with heartrate during manually selecting Swimming and Treadmill activities.
For example when on a treadmill set to manual with a 8% incline, 3.8mph at 25 minutes I start the Treadmill activity on the VA4. I don't change the treadmill's settings at all and expect my heartrate to gradually increase as time goes on. However, my heartrate stays at 65-90 bmp for the first roughly 19 minutes then around 20 minutes it suddenly jumps to around 140 for the last 5 minutes of the workout.
While using the Swimming activity I have found that I can no longer get my heartrate above 150 bpm. In the past I could push myself and occasionally get to 165-170 bmp. Now I just sit around 120-145 most the swim according to the watch.
Either I became really fit overnight or this 6.80 has some bugs. Maybe the Swimming activity is accurate but the Treadmill activity is so far off it can't possibly be right.