On the Venu 3 the 2 LED HR sensor runs, except for when Venu 3 is recording an activity or broadcasting HR via Bluetooth. During these time it fires up the better 4 LED HR sensor.
The 2 LED sensor seemed to be stuck at ~86bpm, even when indoor cycling (but not recording on the Venu 3) with a HR of 140+bpm (as displayed on Edge 830 + chest strap HRM).
Today after the 7.07 F/W install, the 2 LED HR detection seems to be fixed!
It tracked extremely well as compared to the Edge with Chest strap HRM.
Thanks Garmin !
Barry