When we first got our Alltracks, both of us had issues with our phones working initially with Android Auto. The only we could get it to work is to connect our phones before we start the car and then it mostly worked. After about 20 or so connections, the system normally works as intended and one can usually plug in the phone after the car has been started. But we've found a few peculiarities.
If I drive my wife's car, my phone won't connect via BT the first time I start the car, but will connect nicely the 2nd time (and therafter.
My wife's phone won't connect to her the first time if I have been driving her car.
The above weirdness is also on my car when my wife drives it.
Also, on AA, the system will (after start) switch to Google Maps by itself and mute the radio. Pressing the Radio button turns the volume back up to the earlier level and then manually switching to Maps leaves the radio on. I'm not sure if this a AA issue or a VW issue.
Both cars are identical with the exception of the exterior color (2019 Alltrack SEL) and the phones are the same (LG V20 on T-Mo)