Improve Related Products

Hi there,

I hope I have created this thread in the right place. I’m using this custom code to display related products based on a specific attribute, but it doesn’t work. Could you please see if I’m missing something here?

function custom_related_product_args ( $args ){
    global $product;

    $cats          = wc_get_product_terms( $product->id, 'product_cat', array( 'fields' => 'slugs' ) );
    $brands        = wc_get_product_terms( $product->id, 'pa_brand', array( 'fields' => 'slugs' ) );

    unset( $args['post__in'] );
    $args['tax_query'] = array( 
        'relation' => 'AND',
        array(
            'taxonomy' => 'product_cat',
            'field'    => 'slug',
            'terms'    => $cats,
        ),
        array(
            'relation' => 'AND',
            array(
                'taxonomy' => 'pa_brand',
                'field'    => 'slug',
                'terms'    => $brands,
            ),

        )
    );

    return $args;
}
add_filter('woocommerce_related_products_args', 'custom_related_product_args');

Many Thanks