macOS Catalina seems to have broken a lot of older apps. This seems to be some sort of issue with file selection dialogs causing the app to hang. I'm hoping this is an issue on their end and that it will be resolved in the upcoming 10.15.1 update (currently in beta).
If it still isn't resolved by then, I'll look into what I can do on my end, but it may not even be worth the time or effort to investigate as the upcoming version 2.0 of the app will replace the current version 1.x.
To anyone who uses the macOS version of the app, I suggest staying on macOS Mojave or lower for the time being.
Best Regards.