(Chat User)
When I downloaded the one image you had up, when I tried to open it in Photoshop it gave me a phrase error.
I have noticed two reason this happens one you might have changed the file from a jpg using file renamer program.
Or you modified the template using notepad instead of using Wordpad because notepad adds junk code that can mess with how things are downloaded. When you make modifications to your template in cpanel make sure you open as a UTF 8 and not as a windows 1252 or 1251. I would check the details.html page make sure you can open it in the 4image cpanel edit templates and if it's blank then you need to go to the cpanel open it with encoding UTF 8 and save it again see if that helps if not
I think you can in PSP batch convert files to gif and see if that works.
I hope that makes sense if neither of that works I'm at a loss. I'll check on your site later see if you found an answer.