Yes have used Apple cable.Yet to pick up ours from the campervan converter, but the dealer mentioned this when we were speccing it. TBH he advised not to go with the Discovery Media unit which was decent of him and just use app connect BUT he said that you absolutely had to use the Apple grade USB cable, or a very decent quality one at least, otherwise it would not work... Not sure what cable you're using...?
Just make sure you try it whilst your there on collection day.Just ask for a quick example how to use it. Sort any issues out there and then