I have the XT926, running TWRP 2.8.5.4 and the lasted CM12 nightly. I tried out the new Android Auto app from the Play Store. After realizing it required a compatible vehicle or head unit, I uninstalled the app. Before installing this app, I had no issues using the dock. Now every time I drop it in the dock, it shows that car mode is enabled (like it always did), shows it is charging (like it always did) but a new message comes across the screen that says something to the effect of "select your device from your car's screen". Well not only do I not have this option, but the few times I have succeeded in getting rid of this message and played music through the Play Music app, it only comes out of the phone's speakers, not through the car like it used to.
I have gone so far as to do a clean flash and I didn't reinstall Android Auto, obviously, but the message still comes up. Any suggestions?