Trying to use WP_Query to display a custom post type

Question

I'm trying to use WP_Query in function.php to display a custom post type on a certain page.

I just can't seem to get it to work, can anyone see issues with my code? nothing is output at all and there are apparently no errors.

/*** add venues to venue page ***/
add_action( 'woo_post_inside_after', 'venue_loop' );

function venue_loop() {
  if ( is_page(123) ) {
    $args = array(
      'post_type' => 'tribe_venue',
      'orderby' => 'title', 
      'order' => 'DESC',
      'posts_per_page' => 10
    );

    $venue_posts = new WP_Query($args);

    if ( $venue_posts->have_posts() ) { 
      while( $venue_posts->have_posts() ) { 
        $venue_posts->the_post();
        $output .= '<li><a href="' . get_permalink() . '">' . get_the_title() . '</a></li>';
      }
    }
    return $output;
  }
}

Answer 1

Typically, you would be echoing content from an action hook, rather than returning it, and from I can find about this Woo Theme hook that looks to be the case here too.

Try echo $output; instead of return $output;

See:
Clarification on filters and hooks
Difference Between Filter and Action Hooks?