Comment Optin not working

Hi could you help me with this, please?

The option to subscribe when you comment is showing up. However, when the option is used it doesn’t seem to send the email address to mailchimp, so the commenter’s email neither show up on my list nor do they receive the double optin to confirm their subscription email.

Here’s a page:
http://fitsynthesis.com/health/post-2/

If you could help me get this to work I’d really appreciate it, because it is a very nice feature.

Thank you

https://wordpress.org/plugins/mailchimp-for-wp/