Search orders by item order meta

I have downloadable products in my Woocommerce store that have associated serial numbers which I store in the ‘wp_woocommerce_order_itemmeta’ table. My customer service folks need to be able to search by serial number and bring up the order that has the product with the searched-for serial number. I tried this in my functions.php file:

add_filter( 'woocommerce_shop_order_search_fields', 'woocommerce_shop_order_search_licensecodes' );

function woocommerce_shop_order_search_licensecodes( $search_fields ) {

  $search_fields[] = '_licensecode';

  return $search_fields;

}

but I am not getting any results when I search for the serial number. Any ideas what I can do to make this custom search work? Thanks!

https://www.ads-software.com/plugins/woocommerce/