I talked to the EECS department today about why I have a four-digit bill for tuition that they said they would pay for. Apparently, there was a data entry error, and whereas in-state students pay fees but no tuition, out-of-state students pay both. Thus, the department somehow managed to miss that I was out-of-state in one of the various spreadsheets and has not yet paid for my tuition bill.
This will be resolved by the end of the week, and I will have my registration block removed.