I have run in to the same issue, but I'm on PM 4.5.4 (running on Mac Leopard) which doesn't have the metadata deletion tool.
When uploading to Sam's Club, however, you have two choices for selecting the images. You can click on a button called "select pictures" in which you navigate to the right folder on your machine. That approach shows "failed photo" as discussed above. But if you use the drag-and-drop approach, in which you select one (or a group) of photos from your Finder (on Mac) and drag them onto the target area on the website, it seems to work fine.
Hope this helps,
Kevin