Hello, I want to add Custom Registration Fields to MailChimp List. So I followed the tutorial on merge tags for MailChimp https://s2member.com/kb-article/can-i-add-custom-mail-merge-fields/
I have created s2-hacks.php file in /wp-content/mu-plugins/
When I test the registration only Fist Name, Last Name and Email Address are added to the list and no other fields.
Please check the screenshots of my code snippet and merge tags in MailChimp
