Hey all, So I've been fairly disappointed by my heart rate sensor so far. I've gone for a run and a bike ride and both times the workout app says the chart is unavailable. The info button says there wasn't enough measurements to create a chart. I did sync with Strava, which shows the heart rate anyway (I suppose they don't have the same qualifying criteria for display) and you can see below that they're both really bad. Maybe a few dozen measurements with interpolation in between. Is this sort of behaviour expected? I'm guessing not. I did tighten up my strap before use both times. I used to have a fitbit surge which measured my heart reate very consistently - but comparing the two I would have expected that apple to blow that out of the water. Am I looking at a warranty situation here? Should I contact best buy, or is there something else I could try?