I have that problem with PS. It tells me my thumbs are below the 15kb level, but when I upload r'osity tells me they are more. Wonder if the PS forum has any ideas? I have been using gifs as thumbs to get over the problem, but of course the quality is way down.

The greatest part of wisdom is learning to develop  the ineffable genius of extracting the "neither here nor there" out of any situation...."