Why can't I hear background/supportive vocals with headphones on?

[Elias127]

I'm playing this song California Dreamin' on my new Beats (Solo 2), and I can't hear supportive vocals, only the lead singer. This is on the iPhone. When I plug my Apple earphones in it works fine.

I have tried them both on my laptop too without issues. Only the combination of Beats+ iPhone gives this weird sound. Does anyone else experience the same issue? Any solutions?