I have a WooCommerce site and am working on the product tag pages. I want to display every product that is assigned to that tag, and break them up into their individual categories (this bit is working).

The only issue I am having is it is displaying every single category, even if 0 products in the current tag have that assigned.

<?php $tag_id = get_queried_object(); ?>

  <div id="product-list" class="product-list">

    <?php // Get all products inside the current tag ?>
    <?php $collectionProducts = array(
      'post_type' => 'product',
      'order' => 'ASC',
      'hide_empty' => true,
      'parent' => 0,
      'taxonomy' => 'product_tag',
      'field' => 'slug',
      'terms' => $tag_id->slug
    );

    // Get list of categories, but only display them if they have products with the current tag assigned 
    //(THIS BIT ISN'T WORKING)

    $child_terms = get_categories( array(
      'parent' => 0,
      'hide_empty' => true,
      'taxonomy' => 'product_cat',
      'tax_query' => array (
        'taxonomy' => 'product_tag',
        'field' => 'slug',
        'terms' => $tag_id->slug,
        'operator' => 'IN'
      )
    ));
    ?>

      <?php // List products, broken down by category ?>
      <?php foreach($child_terms as $child_term) { 
        $shortcode = do_shortcode('[products tag="' . $tag_id->slug .'" category="' . $child_term->slug . '" per_page="-1" columns="3" orderby="date"]');
      ?>

        <div class="product-list-single-category" id="<?php echo $child_term->slug; ?>">
          <div class="title">
            <h3><?php echo $child_term->name; ?></h3>
          </div>
          <?php echo $shortcode; ?>
        </div>
      <?php } ?>

    </div>