@lbenerza. Thanks for posting. If the position in the module is ‘listing_position1’, then the short code should be {loadposition listing_position1} and NOT {loadposition listing_position_1}.
Also, make sure the “Content – Load Modules” plugin is enabled. In addition, the module must be assigned to either all the pages or the specific menu item page that the article is specified. All of this is explained in the documentation.