Bruno, the After content setting means that the attachments will be added to the end of post content so it will work automatically if the template (for example single.php) makes use of the_content() function. If it doesn’t work automatically we may assume that this is either not used on selected template or is being modified (via apply_filters()).
In that case please make use of the shortcode – just add this in your template files. This way you can display attachments after short description, in product Tab, anywhere you need.