I'm on Windows 10 right now, running a 1440p display, and a 4k display at a logical resolution of 1440p. Lots of stuff misbehaves on the scaled 4k display.

For a couple of examples: The nVidia Control Panel ignores the scaling on the 4k display and renders tiny text as if the display was set to 4k. GPU-Z looks like a blurry mess.