This is a side effect for certain applications and games when running on multi-adapter systems. The behavior is triggered when the user (or Operating System) moves these applications from a display connected to one graphics adapter to a display connected to a different graphics adapter. When this happens, the application needs to properly handle the change in display adapter to transition without interruption.
In Optimus notebooks, the internal LCD display is connected to the Intel Integrated Graphics adapter and the HDMI output is often connected to the NVIDIA graphics adapter. Since this is a multi-adapter configuration, some applications will show a black screen if the user drags the application window between the displays of the two adapters. The same happens when the user plugs/unplugs an HDMI display and the OS automatically moves the application to that display. This behavior is specific to the application's handling of multiple adapters. Other applications, such as Windows Media Player, properly handle multiple adapters and should function correctly.
To address problems, the user can close and re-open the symptomatic application after dragging it to the desired display, or re-launch the application after setting the desired display to be the primary display in the Windows Display Properties Control Panel. You should also ensure all updates for the application have been installed, as the issue may have been resolved through a patch from the software vendor.