I was riding a pre-uploaded course and was off course, device keeps asking me to perform a U turn.
Heart Rate Monitor numbers were crazy high! I can't manage higher than 173 and while cruising along I'm seeing 200bpm+.
Nothing I tried would fix the HMR numbers.
Finally I got fed up with the U-Turn requests and Stopped the Navigation, HRM numbers immediately return to normal and remain there for 65 miles.
Not necessarily looking for a solution, just reporting this as another data point.
Barry