I have seen this reported before. In the incidents I looked at the issue was the image files were in a format that the system does not accept. The formats the system does accept are GIF, JPEG and PNG. The images that were not uploading were in a format known as the Exchangable Image File Format even though the file names had ".JPG" as an extension. This Exchangable Image File Format is used by digital cameras including those in smartphones. I would suggest that you check the setting of your camera/smartphone camera app to see if you can tell it what format to save the pictures with. You may also want to convert the images in question to JPG format on a computer. A great free program for doing this is
PIXresizer.
If you are still having issues send me a PM.