Thank you for contacting. Your problem seems to be a theme specific problem. The plugin is independent of default or main featured image. It looks like your theme haven’t enabled featured image functionality. In order to enable featured image functionality to your theme you can add add_theme_support( 'post-thumbnails' ) in your functions.php file. You can refer this tutorial for that.
The featured image you are referring in the screenshot needs to be enabled by the theme. Sorry that you were confused by that screenshot. Refer the third screenshot, there is no main featured image in the screen shot. There is “Featured image 2” and a mouse clicking “Add new” link to generate next featured image “Featured image 3”. That’s exactly the plugin is for.
Please remember that this plugin only simulates the functionality of featured image dynamically. You can add multiple featured image dynamically and get it in your theme using some simple functions (See documentation here).
The shortcode and fancybox functionality will be available in next version of the plugin.
If you have any problem with the plugin, do contact me.
