I edited my post again. I first though she was a pullet, but instead she just appears to not be laying.Not for all birds though. Do all of your birds do this?
I have seen pullets allow mating. They just do not squat for him. I would guess what you meant is that they do not squat until they are near or are laying. Since the hen is so tall, it may be the reason.
She may be a pullet though.
I've seen bantams mate LF hens. These ones are a pretty similar size...