Hi Kristy, Just spitballin', but here's my theory...
the images are stored somewhere (cough-Amazon-cough) on the internet
for security purposes, the image links redirect with a quickly-expiring instruction passed as part of the request to view the image
by including the url column explicitly, that quickly-expiring instruction is refreshed (and valid), so the image is "available" for your image column
without the url, however, that quickly-expiring instruction is neither refreshed nor valid, so the image is "not available"
since this is new behavior, perhaps the quickly-expiring instruction has been recently added and/or sped up significantly
I look forward to other theories, or (even better) a technical comment from someone who understands and can explain how this in fact all does work. Regards, Doug Doug Den Hoed - AtAppStore