My 2015 isn't connecting my phone calls to Bluetooth.

So it just started happening a month ago. It plays my music fine. Spotify. But will not connect most of my calls they l through the phone. I reset the settings on the head unit with no luck. Even factory reset my phone in case it was a glitch in an update. My only thought i have left is disconnecting the battery to the car. I have the hybrid model so I don't know how easy that is. I'm all ears on suggestions.