You are correct, my iPhone 6 Plus did the same thing on my Audi's MMI. It showed a connecting phone call on the MMI but nothing on the phone. Weird.
I don't believe it has anything to do with Audi since nothing changed there. We just got new iPhones and/or upgraded to iOS 8!
I've had luck the past 2 days but will let you know if it stops working.
I talked to my Audi technician and he also stated that Apple is working on a fix.
My problem was that the network reset didn't help at all. I believe everything got messed up with all the devices showing up under Bluetooth but I couldn't delete them as they were greyed out. When I signed out of iCloud rebooted the phone and signed back in all the previous devices were gone.
I believe it has something to do with restoring the new iPhone from a backup and some files may have been corrupted.