"Payment methods" billing page is blank

The "Payment methods" billing page is always blank when I try to access it. Consequently, I'm not able to update my payment method using Xfinity's website. Here are the steps:

Go to the "Billing" page (https://customer.xfinity.com/billing/services). Then under "Bill Settings," click "Payment methods." The resulting page is completely blank.

I have tried many things including reloading the page, clearing cookies multiple times, and retrying. I also have no internet issues because I'm able to access other websites just fine.