Gravity Forms checks if the roles editor plugin (Members or User Role Editor) is available. If it’s not then gravity checks the only user capability ‘gform_full_access’ to allow full access to its functionality. If GF detects roles editor plugin it checks the detailed list of user capabilities:

GF grants a full list to the administrator role automatically just in case there is no any capability from this list granted already.

So if you imported roles data with some limited administrator role it may be a reason of this behaviour. Workaround – select “Administrator” role in URE and turn ON for it all capabilities from the list above.