Unable to attach subscription to system

Several hours ago, I purchased a subscription for a physical server that had been used for a free evaluation of RHEL 7.

Now that I have a paid subscription, I cannot attach it to the server.

From the command line:

# subscription-manager attach


Installed Product Current Status:
Product Name: Red Hat Enterprise Linux Server
Status:       Not Subscribed

Unable to find available subscriptions for all your installed products.

From the web, https://access.redhat.com/management/consumers shows my system under both "All Units" and "Systems", in both cases with "Subscriptions Attached" showing zero. Navigating to the system page and trying to attach the subscription from there with the "Attach a subscription" button shows an empty table with "No available subscriptions found." I have verified that the system UUID shown on the list of systems on the web is the same UUID shown by "subscription-manager identity".