If a student's name does not appear in Billing, this often means the filers are not correctly set on the given page and that student has a status not currently being filtered for in the search.
By default, your Billing pages will only show students with an enrollment status of Active. However, you can easily remove the enrollment status filters to view all students, regardless of status.
In most pages, you can click X in the 'Enrollment status' field to see all student profiles at your center regardless of enrollment status. You can also select a specific status you wish to view.