Membership 2 not changing invoice status after payment has been made

This is a Paypal IPN + Membership 2 Pro problem. I have a member who's payment was received but the invoice status is still showing as 'Billed', it has not changed. Paypal sees the payment and Membership 2 transaction logs see the payment as well, but the invoice status doesn't change. This isn't working for one of my member who paid today but worked for other members previously.