Let me know if I should make a new topic, but I'm having the same issue on a 4000NEX.
My 4000NEX is running off RCAs to a Focal America 6-channel amp. The factory harness and wiring isn't used, other than for the rear speakers.
My setup is bi-amped on the front and deck power to the rear speakers:
Deck front RCAs to splitters. Amp channels 1+2 are for my front tweeters, 3+4 are for my woofers.
Deck rear RCAs aren't connected to anything.
Deck sub RCAs go to bridged 5+6 for subwoofer.
No crossover is set in the deck, it is all on the amp side.
Prior to iOS 8.4, my Siri,