Hey everybody,
I just wanted to let everyone know something that I found out while troubleshooting an Android Auto connection issue on my 2020 GMC Sierra, base mode audio/screen, no OnStar. Long story short, I had to disconnect to battery to fix a blank screen issue. Afterwards, my Android Auto would not work (CarPlay worked fine with my wife's phone). After messing with it for a good long time, I discovered that Android Auto seems to be pretty dumb with regards to a vehicle with an incorrect date. Once the battery was disconnected, the date reverted back to some time in 2014...obviously well before today being 1/10/2021. Until I corrected the date (and time I guess) on the truck, Android Auto would not connect.
Figure this may help some people out if they are having connection issues - make sure the date and time on the truck are correct!