Was no notification logged in CBSubs > Notifications? If not edit your PayPal account and ensure you've notifications enabled and configured properly. Notifications are critical for PayPal letting CBSubs know a payment came through. A notification should be logged as either PDT where they returned to the site after payment or IPN where PayPal directly notification CBSubs.
History log has two entries for "User subscription record created with status: R" followed by "Store payment basket" 8 minutes after the PayPal payment.
Then is there a completed payment entry in CBSubs > Payments for that payment? If so it sounds like something interrupted the subscription storage process.