Q. Why can't I see one of my grading columns?
If you tried to hide a column from your students, you may have hidden from yourself and not your students (it happens to all of us sometimes!).
Open the Manage tab and select Column Organization. Grayed out rows are Grade Center Columns that are hidden from you, not your students. Unhide the column by checking the box next to the row and clicking Show/Hide > Show Selected Columns. Click Submit when finished.