looks to me like not enough water at a critical time. this could be from drought/lack of rain, or, as in my case, over planting/crowding.
corn needs a bunch of water from the first sign of tasseling, to the time the kernals are filled. don't know how much per week, but I use a moisture meter and try to keep the level towards the high end of the normal range. some times this means irrigating every other day, if it doesn't rain. this year, I over crowded and even this much water wasn't enough, I had a lot of ears that looked just like your pics. another plot, planted with half the amount of corn, was just fine, really good, full ears of golden bantum.
the other cause I know of would be poor pollination. if you plant a single row, or only two rows, you will not get optimum pollination, but you would see your simptoms randomly spaced over most of the cobs.