Error when sending custom email

I have created a template that uses the woocommerce_email_order_meta hook. The email displays well and when I send it via the Email Templates editor as a test it sends and delivers fine. However when I try to use the template when sending an actual email to a customer through a woocommerce order it fails to deliver and gives an error. I am also using the WooMatrix – WooCommerce Easy Checkout Fields Editor plugin to collect more order meta data from the customer. I am not sure if this issue is with that plugin or this one. Considering I can send the email fine from the Email Template editor I am wondering if it is not this plugins issue?