External images not shown on my site after mass upload on Product Post from ReHub Deal Store Theme

I downloaded the plugin to use external image as featured image and followed strictly the steps of this video (How to make mass import of product feeds to woocommerce, Rehub deals and price comparison (Updated) - YouTube ), to do mass upload using a csv file. But for some reason when the post is ready the image is blank on my site. It only shows up after I enter into WP “Edit Post” and press the “update” button within post edition area. Is there any instruction on how to resolve it?