On iOS 13.2, GCM forgets every paired devices on the reboot of the phone. Every time.
I first noticed it yesterday because reboots had been a while, but since then I have to pair FR 945 and Edge 830 every time.
Pairing is also a PIA with the FR 945. It needs ten and more tries to get it done.
Most times, the app states the device is detected but not in pairing mode (after I had to enter the PIN).