I think you did the right thing here by contacting our support team Lawrence. They will be better equipped to help than us in the forums as any investigation here would likely require your server logs being shared.
I would just work with the team. I presume they have already reached out.
Hi - I get this same intermittent issue - did u find a fix for this in the end?
The issue is due to session timeout and the clock/timezone difference between our ADSF and the Tableau internal clock/timezone. In Tableau it uses UTC time and our ADSF uses PST. So, in the end, our adjusted our session timeout value (wgserver.saml.maxauthenticationage) so that it is greater than the potential time difference between PST and UTC. We haven't seen it since our last modification.
Hope this helps.