I mentioned one problem with "jpg" files. They must be written in lowercase syntax, if not, no image is displayed in preview of detail image: "Image1.JPG" is wrong, "Image1.jpg" is OK.
Yes, I know when I upload the image in Joomla Administration backend, the name is changed to lowercase automaticaly, but it's not only one possibility how to upload the images into Joomla images/stories folder. Is it possible to accept also big letters in jpg files ?