When a user upgrades to v3.5.5, continuing the use of or enabling Global Outlet Groups causes the Switched Rack PDU to become inaccessible. The user will have to wait some time before regaining access to the PDU. Once the user has access to the PDU again, they will need to reset the PDU to defaults to bring the PDU out of the error state. rpdu firmware v3.5.6 and higher solves this problem. Once the firmware is upgraded, users can safely use Global Outlet Groups.
This problem does not affect users with Metered Rack PDU's (AP78XX) due to the fact that this product line does not offer the Global Outlet Group feature.