When compared to the Master Timetable in V9, it is likely that there will be fewer rows when you view the same data in V10. This is because the Master Timetables in V10 do not show blank rows.
This change was implemented as a result of new functionality available in [7B] Class Staffing (a new screen in V10) and  Edit Timetable. On these screens, users can choose which classes are displayed and the screen adjusts to remove any blank rows, reducing the need for vertical scrolling. Removing the blank rows throughout the reports is required to achieve these concise displays.
If this causes issues, adding <Nil> classes under the existing ones in [7A] Class Information can be done in order to make each day consistent. <Nil> classes will appear as blank records on the Master Timetable. It is a good idea to add the <Nil> classes to a group that occurs everyday such as homeroom.