I believe the api has changed. It has something to do with permissions. Could someone please test a new private app and verify for me?
Does your products include images in the response? My is an empty array "images": 
Are you sure the product even has images? A product with none will certainly return images: , the correct answer.
I have never seen a product API call that does not include images if they exist, so my guess is, that is it. If you are sure the product has images and you're just not getting them, then booya... that is a problem. Probably will just go away.