Ryan,
we are having the same issue, with thumbnails not showing up on the front page or the slideshow. I’m going to check if using content/uploads works. If not, I’ll be back. (Because the theme does seem to imply that images attached to each post will appear as a thumbnail. THat doesn’t happen.) I’d be happy with either thumbnails of images showing up on the front page OR categories having a banner instead. Either works for me. And the slideshow working too.