That doesn't sound right. You should be able to press any button by clicking anywhere on the button. This is the first time I'm hearing about such issue. Haven't been able to reproduce it on my machine, but I don't have a macos Catalina machine to test your setup.
Unfortunately, since I cannot reproduce the issue, I cannot fix it. I can refund your purchase if you want and if/when I'm able to test it on Catalina and fix it I can inform you to try it again.
Sorry for the inconvenience.
PS. Does the same thing happen in the online sandbox? http://dls.makingartstudios.com/sandbox/wasm