[Membership 2 Pro] MailChimp not registering existing contacts to new list

Access has been granted..

We have used MailChimp with Membership pro 2 for a few years now and haven't had this this problem until this year.

When someone subscribes to the membership, if they were already a member of another mailchimp list (which is pretty much everyone in her membership programs) their email address is not being added to mailchimp list associated with the new subscription (seating of the divine level 4 and level 4 subscription).

If on the other hand, the member is new or using a new email address not already listed in mailchimp contacts they are added to the list associated with the new member subscription.