Trouble logging into secondary email account using Xfinity website

There are three secondary email accounts associated with my Xfinity account. I have been unable to log into one of those accounts through the Xfinity website.

Here is the sequence of events

1. Go to Xfinity.com, sign in using email address of the secondary account.

2. Am presented with password prompt, I enter the password.

3. I am presented with a page asking me what email address to use for 2FA

4. I select the address shown 

5. A box appears asking me the 2FA code I recieved by email.

6. Typically between 10 and 14 minutes later the email with the code arrives.

7. I  enter the code provided and click ok.

8. I am returned to the original login page that asks for my login credentials.

Obviously I am using correct credentials, I do recieve the 2FA credentials. I am stuck in a loop. Repeating the above steps has the same result. This has been going on for  weeks. Why is this happening? This is new behavior.