Given an unpatrolled contribution for Flow (like this)
When I click the timestamp
And and click on a unpatrolled entry in the new history
And then click on the "mark this page as patrolled"
Then I assume the patrol mark to go away

In this case I get a warning about session error / invalid session.

Error message (in Norwegian)

Gtrans read "There seems to be a problem with your login, and it was canceled for security reasons. Press the Back in your browser and reload the page and try again."

This is an animation of the sequence.

Note that patrolling on nowiki has a slightly weird setup. ;)