Polar H7 HR Strap

I just got a Polar H7 strap and paired with Garmin fenix 6 pro. I saw it was connected and did a 4 mile run on treadmill. But I can't tell if the run pulled HR from the Polar or from the watch. NOTE: All i did to pair it was add sensor in the watch and when it said connected, I started my  treadmill jog. i can't tell though if it was the watch recording or the strap.