Why are new and old submissions not working in MailChimp integration.

I've successfully integrated a form with MailChimp however the submissions are not being added to my MailChimp list.

I could not reproduce the problem when I tested my form. Submissions were added to MailChimp.

Please try it again and make sure opt-in isn't enabled in your MC account and in the integration settings. When it is enabled, the user has to confirm the subscription on their email first before they are added to your list.

It seems to work after unchecking the opt in. (Double opt in on MC.)