Aux input plays out of LHS speakers only

[cein10]

Hi guys,

I'm hoping someone can shed some light on an ongoing issue when playing audio from my iphone through the aux input.
I have a 2010 bluemotion passat with a factory fitted RNS 510, and when I connect my phone and play audio it only comes out through the passenger side speakers.

I have tried various cables believing this was my issue as well as changing iphone and head unit audio settings.

Am I missing something or do I just have to put up with it?

Any help would greatly appreciated!

Cein