Thanks for reaching out to us.
Sorry to hear that you’ve run into this issue. We haven’t changed anything in this area recently. We’ve always had a 16 megapixel limit on uploads, however we will be lifting this limitation in the next Ribbet update. You should be able to overcome the limit by using the Basic Uploader (below the Upload Photos button on the Library > Get from Computer tab).
If you continue to have the issue, could you please email an example image to support [at] ribbet.com so that we can investigate further?