I had the same issue with RCD-510 it seems like when they implemented the track control and text feature somehow the design messed up the streaming to force right channel both left and right and disregards the left channel. I also had not help from anyone at VW and they had no idea that the issue was there ( they are truly a bunch of jackass ) They claimed it was my fault. Any way I swapped my RCD-510 with a previous model RNS-510 Ver C updated to SW1140. The bluetooth streams fine so the problem is in head units not wiring and not bluetooth 9w7 unit. The rns-510 I have now will not show track info text or track control bluetooth audio from iPhone but the sound is proper and that feature is not the most important thing for me.