IMAP and SMTP work on two Comcast.net accounts but not on a third

I use eM Client (similar to Outlook) on a Windows PC to receive and send email from three comcast.net accounts.  I had to change some passwords recently, but found port and other settings that work fine for two of the accounts.  But the third (primary) account doesn't work when using the same settings as the two that do work.

When I try to setup that third account automatically, the error message is "server was found but authentication failed."  When I try to fix the connections, for IMAP it says "your credentials were rejected" and for SMTP it says "server not responding."  I am using the same credentials that I use to login to the primary account on xfinity.com.

After spending a lot of time with Comcast support via chat without progress, I tried accessing the primary email account using Outlook and that failed as well.

Seems like Comcast is blocking access on this one account.  How can I get that fixed?

Thanks.