Garmin HRM Dual and iPhone XR

My HRM will work with everything except the Zwift app. Things I have do…
Synced HRM to Fenix using ANT
Synced HRM to Edge 500 using ANT
Synced HRM to MacBook using ANT
Paired HRM to iPhone using BT
Turned all devices off and unsynced/forgot HRM including iPhone
Made sure all devices are updated

The Zwift App(iPhone) will ask to Sync with the HRM and does but the app will not recognize the signal. HR reads 0(zero).

What am I doing wrong? Thanks.

Don’t pair the HRM with the iPhone itself. Pair it ONLY through the Zwift app.

I did that. “Forgot” the HRM from my BT list. Open Zwift. Connect to HRM (it connects) but the HR reads zero. Every time.