Cubase Pro 9.5.41, Windows 10 1803 (build 17134.376) with 1070 video card, latest drivers.
(Settings > Display Settings of Windows Scale and Layout set to 150%, 3840x2160 Resolution, quantity 2 - 4K monitors using extended display setting)
Cubase title bar drop down menu items do not work in their proper locations on 4K.
example: the Studio drop down menu will often appear out of position (where file menu should be dropped down) when clicking the File drop down menu if you have a Project loaded and maximized and have Windows Magnifier loaded but only set to 100%.
The error could not be replicated without a project loaded and maximized and windows Magnifier running.
Perhaps a Scaling related interaction between Cubase, Windows and Magnifier?
I have not noticed the same behavior on any other non-Steinberg software on Windows with Magnifier at 100%.