Unitron hearing aids dropping connection to iPhone 11 bluetooth

I have a problem with my Unitron Moxi Jump R hearing aids on my iPhone 11 with IOS 13.1.2. They are Bluetooth hearing aids and *not* "Made for iPhone" hearing aids. I had no problems with my iPhone 6. My audiologist claims it is an iPhone 11 problem; Apple wants me to do a full factory reset which I hesitate to do. I did do a "Reset Network Suggestions" which did wipe out my WiFi and previous Bluetooth settings, but did not solve problem.Any suggestions?

I can pair the hearing aids to the phone. However, when I connect in Settings->Bluetooth the connection lasts for between 10 and 30 seconds and disconnects. When I paired the iPhone 11 to my old MacBook Pro the connection stayed up for many minutes -- although I didn't really have a way to transmit anything between the phone and MacBook to see how good it was.

Surprisingly, when I open the Unitron "Remote Plus" App on my phone, it can connect to my paired hearing aids and the menu works -- for example changing the hearing aid program to "mute" or "car" or back to "automatic" and I can change the volume. So that works the same as the iPhone6.

What doesn't work is getting music or podcasts or audiobooks to play through the hearing aids -- there is no Bluetooth device option for the audio because they have disconnected -- except, once, during one of the longer 30 second connections, I got about 10 seconds of podcast play through the hearing aids before it quit. Have never succeeded doing that again despite several attempts. I have attempted at several locations with more or less electronic noise, but no difference.

I have researched this a bit and my iPhone 6 was using Bluetooth protocol version 4.2, while the iPhone11 is using Bluetooth protocol version 5.0. The hearing aids specs state they are Bluetooth 4.2 Dual-Mode and include some specs that I don't know how to interpret but include here:

Antenna type: Resonant loop antenna

Operation frequency 2.4 GHz – 2.48 GHz

Modulation GFSK, Pi/4 DPSK, GMSK

I have been told that Unitron is communicating with Apple, but I would like to be able to tell them to "hurry up!". Or just find a solution!