I am also very frustrated by the elimination of the manually unlock a quiz for a student option in New Quizzes.  Why on earth was this essential option removed?

New Quizzes is problematic in other ways.  For example, there is no way to edit the quiz questions in the normal EDIT mode (via the Assignment tab in the side menu). The only way to get to the edit mode now  is to click on the quiz name at the top of the grade book column for that quiz.  Why was that silly change made?

One would think that a feature named "New" Quizzes would be an improvement from the Old Quizzes model...but so not in this case.  As a long time Canvas user, it seems New Quizzes was designed by programmers, not users.