Let's not fool ourselves here guys. The accepted answer only got the user to his goal.

The very first problem lies here:

    <?php
    // display upsells and related products within dedicated div with different column and number of    products
    remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products',20);
    remove_action( 'woocommerce_after_single_product', 'woocommerce_output_related_products',10);
    add_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products', 20);


An action is removed, and then placed in the EXACT position it was removed from. The goal is completely unclear.

I came across this with a search on the related products because I did not understand that TAGS and CATEGORIES are what drives the `woocommerce_output_related_products` function in this plugin.

The best answer to THIS question is the following link, and has everything to do with the `woocommerce_output_related_products_args()` filter: http://stackoverflow.com/questions/23554993/output-posts-relating-to-the-tags