If you change to M7 Marking Period and see assignments your Grade book You should see something like this.
To hide these grades while we do the Class rank calculation you can simply uncheck the Include in Final Grade. For all assignments in M7.
When this is done, it looks something like this
The reason this must be done is that the M7 Grades will affect the current course grades shifting the Students Final Average.
After the Class rank release just re check the Include in Final Grade.