When creating a custom email header for a email template it gives an error in the email's body.
Error filtering template: Email template '' is not defined
I have placed in the header using this convention in the email template body (which is just overridden in the theme email)
I have put the template id into email_templates.xml inside the main module (I know it's bad practice, but for now, please humour me till I fix the main issue)
It is as if it doesn't find it's name for whatever reason or something? It is literally two ' in a row with no name. I did at the time have a - in the label in the section below. It might not have liked that?
<template id="design_email_header_changed_template" label="Header Changed" file="changed_header.html" type="html" module="Magento_Email" area="frontend"/>
I have put the template header in the module under the frontend folder on the root as well as the theme folder (again, I know bad practice, but I'm just trying to figure out what is going on).
I have also updated the config.xml to include the header template:
I am unsure of what I am doing wrong for the system to not retrieve the html file to spit out the template or, rather find the template.