A common mistake is the belief that just because a chicken is a bird that they should lay up high like they were a robin or something, therefor many of the nests provided for chickens are too high off the ground to suit chickens' fancy.
Chickens are ground nesting birds like turkeys, quail, and pheasants are so chickens prefer to nest on the ground but as long as the nest is lower than the roost and like the previous poster said "secluded" they should take to it like gangbusters. If we stop worrying about the comfort of our hens backsides or bending our backs to gather eggs, but instead use a slab of sod or turf the same size as the nest box and install it in the nest, grass side down then add a little straw to ease our conscience, I think your hens will take to laying in the nest.
Like with going broody some hens have had more or less of their natural instinct bred out. So this may or may not work for you but I predict that it will make a difference in most of the cases like your own.
Hens choose nest locations with an eye toward spending 21 days sitting safely 24/7 amongst the night time predators not to make our life better.