I'm not exactly sure when this started happening, but I've noticed that WordPress is resizing my original (full) images to the large size and not giving me an option for large images.
No matter what size I set for a maximum for large images, that is what my full sized image is resized to, and the large image option is grayed out.
If I set the size for large images to 0, then the full image is resized to 1024.
This happens when I switch my theme to Twenty Eleven, so I don't think it's my theme. I don't believe it's a plug-in either.
How can I get my large images back and retain the size of my original images?