A slight thread resurrection, mine was perfect, controlling from the Nav 6 and Jog wheel, it then I installed iOS11.
I wonder if anyone else has tried with iOS11 beta, but it went back to the "downloading from apple device" to " failed to communicate with device".
Apple have changed the file system for iOS in 11 so possibly this is the culprit?
I rolled my iPhone 7 back to iOS 10.3 last night and the Garmin, the iPhone and the Intercom are all perfectly aligned again, with album artwork, browse function etc all restored.
It would be interesting to see if anyone else has suffered this, and obviously iOS 11 is in beta, but are Garmin on the case because I can imagine a firmware update on the Nav 6 being needed.