Have used black oil sunflower seeds almost exclusively in my platform feeder for several years and have always had many birds Winter and Summer, until recently. The cardinals, finches, bluejays, etc. have not been staying at the feeders. They stop by briefly but move on. It appears that the seeds that I have (40 pounds bought at Tractor Supply) do not have much or any meat inside the hull. I wonder if anyone else has experienced a similar problem?