Originally Posted by Steve

That happens some times.
It's a pollination problem. Those tiny kernels on one side didn't
receive any pollen so they never developed. Either the silks for that
side never emerged from the husks or, more likely, a pest ate the silks
for that side before pollination occurred.
Poor pollination can also occur in plants on the upwind edge of the
patch because most of the pollen just blows the other way. That's not
your situation because that tends to produce hit or miss kernels all
over the cob and not one good side and one bad side.

Steve