We have recently discovered that images with spaces in their filenames will not work properly on the Trading Post site. When an image has a space in the file name (ex: my image.jpg) that space gets converted to %20 (ex: my%20image.jpg) when the image is served. These images will display properly in your description (Ad Template) but will not show up as Gallery images or as the main product image at the top of your listing. Trading Post is aware of this issue and is working on a fix.