Please reopen the ticket with Tableau Support via a reply to the original email thread to get personal assistance with this issue. There are many variables in play with SAML and it is better to get assistance for troubleshooting. Please feel free to share what you learn as the root cause with the community though.
We are also facing the similar issue and getting the below Error message from the Tableau Desktop
ERROR 6: SSL handshake failed
Please confirm if you were able to find any solution for this issue.