I don't think you looked at my site on this one. I just downloaded via ftp the images that are displaying in the above screen, and they are exactly as shown in the screenshot above. I am attaching one of the files to show you what the module is selecting,
I just downloaded the module from you site, version 1.0.3, and these are the same images displaying on my site. The shadow images are what your module is set to display. You say you are seeing true thumbnail images. How is that possible?
Look at module, unzip it, look at ...modules/mod-jacontentlisting/tmpl/layouts/layout-14/thumb.png
Tell me what you see. If it is not a shadow image, then please send me all the thumbnails you have for this module so I can fix my site. Thank you.