No it's not cache issue. I added this comment on the original post = but I think you were answering while I was adding
Oh, I figured it out maybe - It picks up the image associated with the last sub-category. So now my question would be how to change that to choose the one I want to use.
So in this case I have three sub-cats, if I arrange the sort order so that the one I want to show graphic is the last one, it works.
But that is an unusual way to handle.