subscribe tickbox not showing in buddypress registration form


I am using Mailchimp integration plugin on a site where I have buddypress (and bbpress) installed.

the site is brand new, and all the users have registered after I’ve installed and set up the mailchimp plugin.

I can see the new users being subscribed to the mailchimp list. that seems working ok, but I am wondering why I can’t see the optin checkbox within the register-account form..

and also, if I edit their profiles in backend, they all have the checkbox unticked (as if they weren’t subscribed to the list).

I know that the tickbox in backend won’t subscribe/unsubscribe the user, but it would be very handy for me to double check if a user is subscribed or not, so I might create a list and in a second moment send them another proposal to subscribe.

I have set up a mailchimp API key and added it to the plugin’s settings.

am I missing some other important setting?

thanks for helping!