We suspect this to be related to a recent Windows bug that causes conflicting registry keys within the UAC.
Please follow these steps as a solution that should fix the issue:
Go to the Computers screen of the AE admin portal.
Select one of the machines that are experiencing the issue by checking the checkbox.
From the Actions menu, set the UAC setting to Maximum.
Wait 10 minutes for the change to propagate and then test the machine again. If it works, you can set the UAC to the recommended setting of On (Dimmed) or your preferred setting.