It works for me on a variety of versions of ue4.
And it should work.
You could go to “Advanced settings > editor preferences > Keyboard shortcuts > Common Commands” and see if the controls are set properly, if not press “Reset to defaults” or edit them manually.
Keep in mind, the copy can skip a bit to the right when “Ctrl + w” is pressed, or when you “Paste” it might be close from where your last mouseclick was.