filtering custom post types by all categories matching

 //get the post's terms (troubleshooting - can be removed once figured out!
$category_terms = wp_get_object_terms($post->ID, 'category');
if(!empty($category_terms)){
  if(!is_wp_error( $category_terms )){
    echo 'Terms <ul>';
    foreach($category_terms as $term){
      echo '<li><a href="'.get_term_link($term->slug, 'category').'">'.$term->name.'</a></li>';
    }
    echo '</ul>';
  }
}
//get post terms done
    // get the custom post type's taxonomy terms

    $custom_taxterms = wp_get_object_terms( $post->ID,
                'category', array('fields' => 'ids') );
    // arguments
    $args = array(
    'post_type' => 'program_listings',
    'post_status' => 'publish',
    'posts_per_page' => 5, // you may edit this number
    'orderby' => 'rand',
    'tax_query' => array(
        array(
            'taxonomy' => 'category',
            'field' => 'id',
            'terms' => $custom_taxterms
        )
    ),
    'post__not_in' => array ($post->ID),
    );
    $related_items = new WP_Query( $args );
    // loop over query
    if ($related_items->have_posts()) :
    echo '<h2>Other Programs in this category</h2><ul>';
    while ( $related_items->have_posts() ) : $related_items->the_post();
    ?>
        <li style="margin-left:10px;list-style:none;"><a href="<?php the_permalink(); ?>"
                   title="<?php the_title_attribute(); ?>">
            <?php the_title(); ?></a></li>
    <?php
    endwhile;
    echo '</ul>';
    endif;
    // Reset Post Data
    wp_reset_postdata();