I am having the same issue on Mac 10.12.6 but with Cubase 10 & 10.5. I just purchased Split EQ. Having read the previous entries I unchecked the the onboarding/tutorial box, stoping the the onboarding/tutorial from opening at startup. Cubase still crashed but next time i reopened Split EQ it closed just fine. As a test I opened the the onboarding/tutorial from the dropdown menu and the plugin crashed when I closed it.

Also if I have opened the the onboarding/tutorial and I uncheck “always on top” cubase crashes immediately. A very minor bug for an excellent plugin.

Regards,

Rob