I am not sure its a bug but it is annoying as the system can only have one active connection and no easy way to switch.
iOS phone - I am not connected to CarPlay but audio source is something other than BT, unable to hear BT via system/speakers. And no easy way to change audio source to BT other than several screen swipes. Example - quick few mile destination mapped on my phone at home and go sit in the car - too many turns on the map - want to hear them on the speakers but audio source is set to SXM. Not easy to change to BT audio. You may ask why not connect to carplay - reason is it disconnects me from wifi and my wifi is ON by default when close to home or work and dont want to disconnect wifi (same issue if I choose to try to ATT hotspot via wifi). I do tend to use carplay as needed but choose not to turn it on by default at this time as I want to see and use Sync system.