Updated My Cubase Pro to 10.0.30 about two weeks ago. I am running High Sierra that is fully up to date. Over the past weekend I had to open and make tweaks to several projects that were created in an earlier version of 10 pro. While opening these projects I would switch to the mixer and the left zone would be entirely blank and wanting to hide the input channels to get them out of my way would click the “hide/show left zone” button on the tool bar and I was right back to the desktop and it took a long time for my mac to even tell cubase had quit unexpectedly. This made it a nightmare trying to re-open 25 projects and it happened over and over on me. Not on every project mind you but it kept happening far too often until I finally found that when I noticed the left zone was empty I could close the mixer and then reopen it and it acted fine and avoided the crash. Not sure if anyone else encounters this but thats a quick way around it. Just putting this out here incase it can help someone else.
It sounds very similar to this. Do you have an example project, where you can reproduce it, please?