Problem on Membership 2 Pro Manual payment

I'm testing the plugins and already have more then 500 user that I want to add to a Subscription, it's ok so far.

I'm having problem when a new user try to subscribe using a Manual Payment. In Billing page I don't see the button 'mark as paid' and even when I click to edit the billing to mark as paid in the the select box the user is not been assigned to the subscription.

Other thing! Is there a way to search for the email in billings page? If not That'd cause me a lot of pain because I have a lot of new users a day but I need to verify manually with the email they send me.