FCA won't support this upgrade, therefore, the dealers will not do it. Seeing the issues in this forum, FCA cannot seem to support the factory installations either!I have a question related to this thread: why can't you upgrade the 8.4" if it didn't come originally in your Jeep? I mean, it's an OEM radio for Pete's sake. Can't a dealer just put it in your build for you?
It isn't a matter of it not working. As you point out, they put it in at the factory. FCA knows how to make it work. They know your Jeep configuration, and should be able to sell you any deltas.
For some reason, FCA does not support anything you add to your Jeep after manufacturing, This includes Mopar accessory kits that they sell, and that use the same parts that are put on your Jeep at the factory. Last time I checked, Mopar and Jeep were both part of FCA. Yet, this is what I have been told directly by FCA. Mopar guarantees their kits to work, Jeep says they are not supported. FCA should fix this communications mismatch, in their customers interest.
This is why folks with some experience with Jeep advise folks to order Jeeps with everything you want on it, and do not plan to add anything to it later.
This policy really, really dumb. You cannot reasonably argue why this is even necessary.