Garmin app not displaying heart rate from Chest strap heart rate monitor.

I have tachycardia. It fluctuates. My doctors recommended a garmin chest strap to monitor my heartrate. It’s not displaying my heartrate in the garmin app despite being paired to my phone through bluetooth. I’ve tried turning my phone off and on again, restarting it, closing the app and reopening it, deleting the app and redownloading it, unpairing and re-pairing. None of it is working. No similar situations are listed on the website. Nothing in the manual helps.