I'm just guessing, but do you have any greater than 4k/24fps content? As far as I've personally seen, I haven't seen any. All of my 4k BDs are movies and likely shoot at 24fps. I'm just guessing and could be wrong but I suspect that for now 60fps is primarily for gaming. Is your display capable of 4k 60fps?
Beyond those guesses I'm pretty much out of ideas.