Cheers everyone. I just went to install aux cable for my e53 and it did the same thing this time it did last.
I got everything pulled apart and clicked the aux connector in the harness without issue.
Before buttoning it all back up, I tested and everything went fine.
Then I run the cable to the lighter hole, screw everything back down. And voila, nothing. It doesn't recognize that I have an aux signal.
Pulled it all back apart and can't get it to work again.

Any thoughts?