Can't select newsletter opt-in only in Mailchimp module

[ukclearance]

I have just set up the mailchimp module, i choose the option to only import customers who have opted into the newsletter click save, but then it reverts back to No. Any advise on how to resolve this? As I don't want to send newsletters to those who haven't opted in. I am using version 1.1.3 of the mailchimp module, and v1.0.3 of TB

[ukclearance]

No multistore is disabled. Funnily enough i thought i would test syncing my email lists with mailchimp and it appears to have only synced those who had subscribed to the newsletter even though the option for opt in only was still set on no.