Pro Sites Isn't Renewing Subscription For Sites Using Paypal Express.

We're having trouble with Pro Sites. It seems to be having trouble renewing the subscription for sites using Paypal Express. We received this error:

User creating new subscription via PayPal Express: Problem creating the subscription after successful initial payment. User may need to renew when the first period is up: Profile description is invalid

What does this mean? We've gone through the settings very carefully and believe everything is set up on our end correctly both in ProSites and in Paypal.