On both Catalina and Big Sur, the scrolling direction seems to randomly revert to "Natural" and I can't change it with the app anymore. The custom actions all stop working when that happens.
The only way to fix it is to restart my laptop. It happens once every few days and it's really annoying. It happens with both the stable version and the options+ beta. There are tons of people complaining about the same thing since a long time, this bug should be your highest priority with this product.