No turn-by-turn navigation on Android Auto home screen in car

[AC Question]

Hi there! I recently switched from a Note 5 to a Nexus 6P, and I'm having some trouble with the navigation features in Android Auto when it's connected to my car. The home screen still has shortcuts for directions to places I go regularly or have recently searched for, but if I tap one of them (or use voice commands or select a destination from within the map screen), it goes to the map screen and starts navigation, but when I go back to the home screen, the green turn-by-turn navigation card doesn't show up. I still get vocal directions (where to turn, et cetera) and the map moves along fine on the map screen (as does the green section with the turn-by-turn on that screen). This was a feature that worked perfectly when using AA in the car with my Note 5 and I really would like it to work with the 6P. I've gone through both phones, comparing all the settings I can think of, and I've reinstalled the app and enabled all the permissions for it, but I'm afraid that this might turn out to be one of those lovely AA quirks. Does anyone have any ideas for stuff I might not have considered settings-wise or am I just out of luck? Thanks for your help!