Please have a look to the screenshot from Board Academy.
In the third step "Set the second Cube to "SET- DE - Actual Months" and select the blue checkmark to save."
This step is not matching to the screenshot below. The screenshot shows the "SET - DF - Actual Reporting Months". Maybe that was the problem for my earlier questions why locking does not work properly for me.
Furthermore, in my environment it is not SET - DE - Actual Reporting Months but SET - DF - Actual Reporting Months.
Why there is also an upper part populated I do not know as there are no working steps about it in module 306 (so far).