Through trial and error I have the following:
1 - The phone and aides connect at startup of hearing aide > all is normal
2 - IF you set the phone down and walk off past the bluetooth range the disconnect occurs
3 - Upon return to proximity of phone the connection is restored perfectly for control of the hearing aide - volume and program. This works and reconnects after separation - no problems
4 - The iPhone has a channel for streaming - or listening compatible device...THIS is the communication path that DOES NOT restore after a phone/aide separation.
So in summary the disconnect is in the listening / streaming communication path but NOT in the control channel. I cannot tell if it is the iOS update that caused the problem OR if the firmware update (at the same time) to the hearing aides is at fault. I can reconnect easily by rebooting the hearing aides when in proximity to the phone. Oddly enough sometimes only one ear reconnects but there we are. Frustrating at the least.