I'm a bit of a newbie. Are you saying that if the iphone video is in .MOC format to load it into GoPro Studio and convert it to cineform? What is cineform? Sorry for my ignorance.
You don't need Cineform.
I have an iPhone 5S. Video from that are .mov files.
No problems at all dragging and dropping them to the timeline in even my Vegas 10.
iPhone 6 shouldn't be any different.
I would make sure you have Quicktime installed (even the free non-pro version).