At this point it’s strange for Steinberg to keep High Sierra listed as a supported MacOS. It’s just going to lead to more reports like this. Especially since it seems to have been more OK with 10.0.20 than it is with 10.0.30 and higher, which leads me to believe it’s not going to get fixed.
Windows has only one supported OS version (Windows 10), and Mac has three listed, although 2 are really only usable.