I use an external heart rate monitor in my running activities.I notice a sudden drop in heart rate that isn't justified by the change in pace, so I attributed it all to a hrm problem. Instead, analyzing the activity's .fit file I noticed that the hrm data is correct but the firmware, currently 18.27, arbitrarily decides to take the data from the fr955's optical sensor so as to ruin all the associated metrics. I saw that you released a new beta that allows you to disable wrist tracking when using an external sensor but currently the algorithm you use to select the correct heart rate source is wrong. Greetings Pietro