Your external display will go black when you try to draw using Word, Whiteboard or similar Apps on Windows 10 version 2004 powered device
This is one design flaw that could affect thousands of devices using the recently updated Windows 10 May 2020 aka Windows 10 2004 version. It seems that if you draw anything in Microsoft Word, Whiteboard, or any similar App, your external display would suddenly turn black.
The flaw makes both the primary and external displays flicker and the external display go black if any Windows 10 2004 user tries to draw in apps like Microsoft Office Word and Whiteboard. Further, the users may also see that their graphic controllers going out of sync in the Device Manager showing a yellow triangle with an exclamation mark in it.
Microsoft issued a special bulletin saying that
If you have a device running Windows 10 version 2004 with a built-in screen (such as a laptop or tablet) and a connected external display set to Duplicate your primary screen, you might see both monitors flicker and the external monitor go black if you try to draw using an Office app (such as Word). This can also happen with some other apps capable of drawing, such as Whiteboard. If you check in Device Manager, your graphics controller will have a warning icon next to it (a yellow triangle with an exclamation mark in it).
Microsoft says their engineers are working on the bug but as of now, they have not been able to zero in on the problem or fix it. There is a simple workaround for the problem. You just need to restart your Windows 10 2004 powered device and all things will be back to normal.
However, you should totally avoid using drawing Apps in the Windows 10 2004 powered devices if you are using the external display for now or you will end up in a vicious loop of drawing and restarting the device and eventually causing damage either to your device or your external display.