Does this still happen if you disable the new video engine introduced in 9.0.30?
An easy way to do this temporarily:
Open Command Prompt as Administrator. Copy/paste:
ren "%ProgramFiles%\Steinberg\Cubase 9"\Components\videoengine.dll videoengine.dll.bak
To restore the video engine: copy/paste:
ren "%ProgramFiles%\Steinberg\Cubase 9"\Components\videoengine.dll.bak videoengine.dll
Or just rename or move videoengine.dll to another place like the desktop.