I’d be happy if this could be a kind of solution:
in the top left corner of a Waves plugin there is a Functions Menu. Just click on it and select the last line - Switch To Generic Editor.
Works in Mojave 10.14.5. + Cubase Pro 10.0.30. + Waves 9 plugins
If you can’t live without Waves Plugins - this is the temporary “solution” until Steinberg really fix it.
Of course this is not the right way to buy that expensive software and do that kind of tricks, it’s neither comfortable nor nice looking but it works somehow without killing your work… at least maybe this is the hint for Steinberg people to find the reason of the crash.
P.S. I’ve read PDF Cubase Manual page by page (as well as YouTube). It’s pretty difficult to find any mention of Generic Editor, as well as the detailed description of Functions Menu. Seems no one doesn’t use that Functions Menu?..
P.P.S. Waves are working in my Cubase Elements 7 without crashing - Mojave 10.14.5. + Cubase Elements 7 + Waves 9 plugins. So does it in Reaper.