Does it work in a normal browser on a PC? If not, you should be able to open the browser’s developer tools and see if there are any error messages in the Console tab or Network tab. For example, mixed content (HTTP on an HTTPS page) is blocked on some modern browsers.
Some of the Fully Kiosk Versions may have a setting for determining how to handle mixed content. FKB Settings > Advanced Web Settings > Mixed Content Mode. Setting this to ‘Always Allow Mixed Content’ should allow HTTP images on an HTTPS page.