See pictures. The OHR sensor is not picking up an accurate HR for the first 5-10 min of my runs. It's showing a steady 138-140 bpm even though I'm very well aware it's in the 170's. It's not until I increase my speed by a good amount that it picks it up and jumps immediately to where it should be. It's never done this before, at least to this extent. It's known to take ~30 seconds to catch up at the beginning of the run, but 5-10 min is absurd. This basically makes the HR monitor (and the watch for my part) unusable. Any advice?