Ha! The other evening after putting on my HR belt before a workout, I entered
Training Mode on my
T3 only to notice that I was displaying "00" for heart rate, despite the watch saying it found the heart rate belt. While at first I was confused, I noticed that the heart rate WAS registering on the dial along the bezel of the watch. Turns out I had the center display set to reveal
Training Effect (which was at 00 because I had yet to start the workout), not HR. I switched back and all was well.