I’m having a similar problem, and no idea how to resolve it. I have footage a client shot on his Panasonic camera which he insists is 30fps, but Quicktime says it’s weird rates like 25.52, 24.05, 30.55, and those are, to my knowledge, imaginary. If I interpret the footage in AE at those numbers, and put them in comps at those frame rates, they increment normally, but add held frames in 30fps comps.
voodoo.