Well, then it isn't because you are shooting at them as that would be poaching.
You know what time of year it is? It is mast crop season. Acorns, pecans, etc. are falling off the trees. Hogs like those more than corn. They aren't showing up because they have something better to eat. Lots of feeder-based hunters have this problem virtually every year. They lose hogs, deer, or both.