I’m not using any email customizer plugin although several plugins do interact with the email flow. Here is a list:
https://ww.wp.xz.cn/plugins/mailchimp-for-wp/
https://ww.wp.xz.cn/plugins/woo-preview-emails/
The preview emails include the meta fields correctly. It’s only when the emails are sent that they are omitted. Does this mean it’s likely a problem with the theme email template?
The theme is OceanWP using Elementor Pro as a page builder (not sure if this effects email templates).
https://ww.wp.xz.cn/plugins/elementor/
Thanks for the reply and the great plugin, worked right out of the box with this one exception.