Apparently this review item was created by a possible duplicate flag, as there is only one close vote on the corresponding question, and a single review with a vote to close.
Sounds good so far, except that the item is no longer reviewable. Why is that? There were never any Leave Open votes, and there's only one vote to close. It seems to me it should still be going to gather either four more close votes or three Leave Open votes.
Is this some sort of bug with flags being handled by the review queue that causes review to complete prematurely?