Monitor Blanking does not consistently occur in Citrix XenDesktop 5.5 and 5.6

Symptoms

Monitor Blanking does not consistently occur on XenDesktop 5.5 and 5.6 when connecting to a physical computer using HDX 3D Pro. This would result in the user sitting at the console of the VDA being able to see what is being done inside the ICA session.

Cause

This is a limitation in XenDesktop 5.5 and 5.6 and is a known issue.

Resolution

Upgrade to XenDesktop 5.6 Feature Pack 1 and use the Remote PC feature, which has been tested with consistent monitor blanking.

Source