Post-inner-content.secondary-content-box not displaying on pages

The post-inner-content.secondary-content-box includes content from 3 plugins and displays perfectly on posts created by admins and pages created by authors (Super Socializer, Wordpress Related Posts and WP Facebook Comments). e.g.

For new subscribers to our website the post-inner-content.secondary-content-box with content from these 3 plugins is not displaying on pages, which they create. e.g.

Upgrading the new subscribers to author capabilities does not resolve this issue. We have also tried disabling all other plugins to check for plugin conflicts without any success.

Please advise what can be stopping the post-inner-content.secondary-content-box from displaying on new subscriber pages.

Hey there

May I know how this content was added here? is this a modification in the theme?
What happens when you use a theme without plugins and customization?