What is this Win10 UE4.27 error - glitched Printscreen (win screenshot)

Win10 and UE4.27

When I Printscreen in win10, and later look at the pics, 50% have this weird glitch.
It happens in BP windows, but also when BP windows are not open.

What is this error called and how to fix?
Very annoying because I Printscreen often to document changes I made in code. But now I cant trust UE4/Win to display and save what my screen did.

  • (This pic is a crop. And parts that didnt show the UE window, were captured fine, e.g. parts of Windows interface. Even parts of UE showed, but others do not. And I didnt have a giant UE tool tip hovering when I PSed.)