An update to Windows 10 released in April 2018 added new Privacy options to the computer’s system Settings. If these are configured incorrectly it is possible that they will block any applications from accessing cameras. Both internal webcams and USB cameras such as HUE are affected by these settings. If you updated from an earlier version of Windows 10, you may have been asked to choose your settings immediately after the update was installed. It is important that these settings allow camera and microphone access, otherwise the software will be unable to connect to the camera and microphone.
If you want to unblock the camera, press the Start button and open the Settings screen, or alternatively press Windows Key + I. You will see an option called Privacy in the list.
There will be sections on this page for your Camera and Microphone settings. Please ensure that the applications you want to use with your HUE have full access to both the camera and the microphone.
Another common cause of video not appearing in this way is third party security software. This separate FAQ includes advice if you believe that this may be the problem.