Joe,
Thanks for jumping in on this. Last night I scoured the log files and nailed it down to something not right with Dovecot (I was wrong actually), as it was not able to authorize the connection.
I then tested to see if Port 110 would work. It did but asked for a password. Which was strange because it has not changed. Put in the Password, and mail started uploading. I then switched back to Port 995 and now that works as well.
I think what threw me was that Thunderbird was giving no warning / error messages at all, until I changed to Port 110.
A simple fix that took 3/4 of a day to find!!!
Thank You - Nigel.