When creating a new report based on the CiviHR Summary template, there are a number of checkboxes under the headings of "Display Columns" and "Group by Columns". There are some discrepancies in what checkboxes are available in the two. Ideally, we should add complete support for any of these items – if that's challenging, then we could instead remove support for incomplete items.
These items are in "Display" but not in "Group by":
-Employee Contribution (%)
-Employer Contribution (%)
These items have different names:
+Job Pay Grade