Thunderbird error 1014

I am the lead account holder for our Xfinity / Comcast account.

All of the users on this account use the Thunderbird email client. 

A few days ago, I helped one of the other family members by changing the password on an account.

When they go to check mail for this account - they get an error 1014.

I've been working with Thunderbird account setups for many years, and know that the account has been set up correctly.
I tried setting up a new user account on Xfinity, set it up in my own Thunderbird, and get the same error 1014.

Thunderbird checks and approves the Xfinity (Comcast) servers but still this error persists.  I've been searching for an answer for several days. This error 1014 has been around for several years.

Thunderbird has worked fine for years with our Comcast email accounts, and suddenly any new account or password change creates a problem.

Yes, third party access is enabled in my settings.  Yes, I have tried getting support though the chatbot and even talking to people, but so far, no solution. 

Frustrated!!!!