There is a temporary issue which may hopefully be fixed soon.
Open the Interface and go to Navigation > General Settings and Alerts and open Access Protection - turn that off and click Apply.
Try a manual update to see if it works. Give it a day or so to see if an automatic update comes in and if it still doesn't work I suggest opening a case with Technical Support, it's free by phone.
I tried your recommendation and it did not work. It appears I have not received any updates since 9-26-15!