I installed the V1 + PerformancePackage mirror wire power cord (similar to the Mirror Tap) in my 2016 M3 today, and I was able to use the green/brown and brown/black wires in the mirror harness for power.
I'm wondering if it's an issue with the Mirror Tap?
This is what I'm using;
http://www.amazon.com/gp/product/B00...ilpage_o00_s01