I just did some more testing and I am seeing it happen with other settings. The ones I just tested were non-SSO related - “Allow users to choose their own language interface preference” and “Display user consent prompt” for the push notifications prompt. The same thing happened with these - unchecked them, saved with the checkmark, came back to the page a minute later, and the changes were not saved.
We haven’t seen this in the past with our settings, though we don’t make updates to them very frequently. This is on Discourse version 2.7.0.beta1.