This is my iPhone. I downloaded a playlist for my car. Notice the last song, The Gambler, doesn’t have that little grey circle to the right of it like the other titles above (didn’t want anyone getting distracted with my awesome playlist so I wiped out the titles!).
So all the songs with the grey circle arrow play just fine in my NX, but The Gambler doesn’t even show up on my infotainment screen. In order to be able to have The Gambler show up in the car, you need to hit that RED DOWN ARROW