Wired Android Auto Disconnect caused by switching to Radio Mode?

I have the navigation head unit in my '21 Venue Ultimate (Canadian). It uses USB to connect with my phone and connects right away. However, if I switch to radio-mode, after a few minutes the connection breaks. I know the solution is to just leave it in AA mode, but my wife likes to use the radio when we drive. So I'm not sure what to do about the wife

Anyway, is this the normal function of Android Auto?