SharePoint Task List Missing Checkbox

Hello, 

We have been having issues for weeks with our SharePoint task list not showing the check box for items we have completed. 

I believe I found the source of the issue by creating a new task list in SharePoint.

It is coming from the calculation based on other columns within the settings of the “Completed” column.

The issue I am now running into is changing the formula to reference a different column so that it updates.

I am not sure how it works or what I can do to update it.

Is anyone able to assist with this issue?