I'm actually trying to modify the Backup Summary Report, which has this same issue. In my example, it’s a fresh, new report with one dataset. I’d simply like to add an Input (like the ones on the Backup Summary Report), but “Add” does nothing at all.

Note that I CAN add datasets - clicking add displays the appropriate wizard on screen.
The documentation doesn’t state any prerequisites:
https://documentation.commvault.com/2022e/essential/input_controls_for_build_your_own_reports.html
What could I be missing?
Thank you~