I use the following AutoHotkey script as a stop-gap fix. Please note that it’s quite an imperfect fix and takes some getting used to. It will mess with your click-dragging on one screen, and mess with your mouse-only clicks on the other. Hold down a modifier key to bypass this hotkey.
#If WinActive("ahk_class UnrealWindow") || WinActive("ahk_class Notepad++")
;==Click fix for correct screen
$LButton::
screenX0 := 0
screenY0 := 0
screenX1 := 1920
screenY1 := 1080
MouseGetPos, mousex, mousey
if (((mousex >= screenX0) && (mousex <= screenX1)) && ((mousey >= screenY0) && (mousey <= screenY1)))
return
else
Click
return