Set all ungraded items to zero in Gradebook
From EdTech Help
Gradebook does not include ungraded items in the course grade calculation. This could result in a higher course grade average for a student if they have incomplete items. To include a gradebook item in the course grade calculation, you must enter a grade of zero or higher. If you want to enter zeros for all gradebook items that have not been graded, you should set ungraded items to zero. This can be done for all students and all gradebook items in a single step.
Go to Gradebook
Select the Gradebook tool from the Tool Menu of your site.
Select the down arrow in the Course Grades column.
Click Set Zero Score for Empty Cells.
You will be prompted to confirm this action. If you are sure you want to assign zeros to all ungraded items, click Update.
Note: You cannot undo this action, so be sure you are ready to assign zeros before continuing!