To automatically start your exercise app on your Sense 2 when you start performing such exercise, you have to enable auto detect for the exercise on the Sense 2 itself. First start the Exercise app (not the shortcut) on the watch, select the exercise you want to start (Run, Walk, Bike), once the Start/Play button appear, swipe up and enable Run/Walk/Bike Detect. That will start the exercise app on the Sense 2 when it recognizes you are performing that exercise. If auto Detect is disabled, then the SmartTrack auto exercise record will start the background. SmartTrack setting is configured by the Auto Recognized Exercise setting in the Fitbit app
