GA: FOY sweet corn harvested; but a bunch of them have zero corns forming

Ooooh YUMMMMM the sweet corn is delicious!  So crispy and perfect!  

BUT a whole bunch of the sweet corn patch has stalks with nothing growing -- the tassels thing at the top yes, but no hint of any cobs whatsoever.  Seems to be a lot of the earlier round of sowing -- maybe too shaded???