Hi James,
Check if you have full access to Gravity Forms itself after activate User Role Editor. It may be related too.
GF plugin itself changes its work with permissions if detects plugin which allows to edit user roles. It requires capabilities from more detailed list in this case. GF add-on may follow it.
Go to Users->User Role Editor, select ‘Administrator’ role and look if there are any not granted capabilities from “Gravity Forms” group.
