I am leaving this here as I wanted other folks to know who may be having a similar issue.
One of my client sites was not charging all international orders shipping fees. After talking through the issue with WooCommerce support for their official USPS Shipping Method plugin, I disabled WooCheckout Editor on a whim and then ran a few test with countries for orders that were not charged shipping and everything worked as it should. This issue is resolved, but mostly wanted to document the issue for Themeco staff and a point of reference for others who may be experiencing the issue.