Woocommerce orderby rand with tax_query not random

Question

I would like to change the related products section on my woocommerce products details page so it only displays related child category products (not products that only have the parent category in common). For Example:

• Parent Cat
  • Child 1 Cat
  • Child 2 Cat
  • Child 3 Cat

If a user is visiting a product details page that is categorized under "Parent Category -> Child 1 Cat" all the user is viewing are "Child 1 Cat" products.

I am attempting to modify the woocommerce/single-product/related.php file inside of my theme folder using the following php scripts to accomplish this behavior:

$product_cat_slugs = array();
foreach (get_the_terms($product->ID, 'product_cat') as $term) {
    if($term->slug !== 'skip-this-cat') {
        array_push($product_cat_slugs, $term->slug);
    }
}

$args = array(
    'post_type'            => 'product',
    'ignore_sticky_posts'  => 1,
    'no_found_rows'        => 1,
    'posts_per_page'       => 4,
    'orderby'              => 'rand',
    'post__not_in'         => array( $product->id ),
    'tax_query'            => array(
                            array(
                                'taxonomy' => 'product_cat',
                                'field'    => 'slug',
                                'terms'    => $product_cat_slugs
                            )
                          )
);


$products = new WP_Query( $args );

The categorization is correct, but my problem is that I am not getting back a random set of posts. I'm only receiving the same posts each load.

Answer 1

It appears that the WP_Query was correct. I am hosting with WP_Engine and I had to contact their support desk and have the ticket elevated to resolve the issue. Apparently the query, even with the 'orderby' => 'rand', was being cached by their servers. I should have contacted them earlier, but I thought it was something that I was doing incorrectly in my query. Thanks all for the help!