I don’t see this behavior. I have to call setZoom (or setZoomFactor()) myself, at least in Cubase 9.0.0.85 on the Mac. Perhaps it is because I have dual monitors, and it always detects the one with normal dpi (regardless of which monitor I have my main menu bar attached to)? How can I run a test such where one monitor is normal dpi and one is hi dpi and get the results you describe?