Frequently bought products - images not appearing

This is happening because Amazon does no longer provide this images on https.

When the user of the plugins has a https capable website, the plugin tries to load images using https but since Amazon does no longer providing them so, it fails.

 

You can see that if you access your website through http, those images are being loaded.

 

 

 

Making the plugin loading http whatever protocol the visitor is accessing your website will not work too, because the web browsers do not allow loading mixed content (http + https) on pages and will block them.