I work as a field scout in Nebraska.  I am noticing the same thing here in a few fields.  Also noticing ears where the kernels are present, but not neatly rowed and lined up on the ear.  They are scattered and twisted around the ear.  As near as I can tell it is from cool temps and/or wide temperature swings during the V6-10 growth stage, and we had both.

However, the field where I am noticing it the most had a late, with drops, application of Roundup.  I am wondering if that may have also been a factor.