Playing Music on Car Radio

I have an iPhone 7 which is paired to my Mazda and my daughter’s Mazda. Up until yesterday morning everything was working fine. Yesterday afternoon however, I found I was unable to play music from the phone through the car radio. I can see all of my music (and contacts etc.) on the vehicle screen but when I select and try to play a track rage screen goes blank and nothing happens. The same thing occurs if I select a track on the phone to play through the radio.

This seems to be the only area causing a problem as I have made a phone call and it went straight through to the radio.

I have not changed anything on the phone or cars so do not understand why this is now happening all of a sudden.

Can anyone suggest a possible solution/reason please?