Empty Email when using Email Template Customizer for WooCommerce

Hi,
We recently purchased the WooCommerce Lucky Wheel plugin and have also installed Email Template Customizer for WooCommerce as per your documentation to enable custom emails per each prize. Creating and assigning of the templates for each prize appears to have worked as expected, however when we tested sending of a custom email, no email was sent. On closer inspection via the WP Mail Logging plugin it identified that the custom templates all have an empty message body and thus not sending. But they are all definitely not empty email templates.

Note: Sending test emails from the custom email templates work, just not when triggered from the Lucky Wheel.