Thumbnails don't display when creating an upload

When uploading a livery the images do not load correctly in the new upload screen. With multiple images, only the first image appears as a visible thumbnail. The 2nd image appears as a green square with jpg on it, and any further images only appear as circular timer icons. This occurs even though a green tick appears to the right indicating the image uploaded successfully. As you can't see which image is which, you have to post the upload, then edit it to be able to look at an re-order the images.