I was just able to reorder some of the chapters in that book without an issue. Make sure that you click "Update Order" and not "Alphabetize." If you click Alphabetize, it will ignore the numbers you have entered. This is the same behavior as VW3.
I could only see an unexpected behavior here if you are changing sort numbers and press Enter to submit, rather than clicking any button. Browsers send an Enter to the first submit button in the form, which is "Delete Selected". However, it is unlikely that a user would ever expect that, since this form is more often used for changing orders. In order to account for this browser behavior and make Enter work for the more oft-used submit button, we will have to reverse the order of the submit buttons.