Hello Galen,
I join this conversation, because Rowan created this thread following to a post I did on Corona's forums. A Corona user has just informed me the new Sustance plugin version was out, so I installed it right away. Unfortunately, it seems somehow broken here ... in Substance Settings :
- Memory Budget and CPU Cores Limit don't show any number;
- clicking Open Dialog for Renderer Compatibility doesn't seem to do anything

- clicking on Apply and Cancel buttons doesn't see m to do anything neither
- the only way to close Substance Settings window is to click on little X on the top right
Enclosed a screenshot of what I get (3dsmax2020.3)
Thank you.