Shortcode in settings panel not work

As the title suggests, the "Add Shortcode" button in the textarea section of the "WPSF Modern" control panel does not work.

I think it would be a very useful function. Is it possible to give us an eye and maybe a fix?

A thousand thanks.

Found the problem and a simple work around.

In class WPSFramework_Shortcode_Manager inside the method shortcode_dialog() the second if statment

if ( true !== self::$is_btn_added ) {
    return;
}

cause the block of shortcode popup window in settings sections. Comment it or remove and work fine.