I have created a new quiz amd added some questions to it. See attached file new_quiz.png for details.
I then clicked on preview and the order of questions look good.
Then when back to edit the quiz and this time I used the reorder tool to reorder the questions. See the attached file new_quiz_reordered.png.
If I now go to preview the quiz, the order has not changed. It is still the same as before and yet when I go back to edit the quiz the order shown is the correct order as shown in new_quiz_reordered.
If I use the arrows to reorder then preview the quiz it looks perfect so it is only the reordering tool that seems to be buggy on my system.