“Gravity Forms Add-Ons” section is provided by Gravity Forms itself via GFAddOn (includes/addon/class-gf-addon.php) class.
My test showed that this group is filled by caps as expected. I may suppose that some active add-on can break the data structures used for this. Try to deactivate temporary all GF addons and activate them back one by one with test repeated to check if this is true assumption and isolate a conflict.
