Summary
No column header is showing up for those Worksheet columns that have an image or icon in their cell(s)

Applicable Products Talent Management:

Salary Talent Management - Incentive

Applicable Releases
11.x and higher

Detailed Information
These Image Columns are not showing their column headers:

Even when their visibility properties indicate that they should be visible:

To fix this, you need to adjust a setting in the "Compensation Settings" section:

After adjusting that setting, the Image Columns will now look like this: