The "one-time access control check" doesn't fire properly if you merely upgrade from Mojave. Dropbox completely stopped working for me until I did a clean reins

The "one-time access control check" doesn't fire properly if you merely upgrade from Mojave. Dropbox completely stopped working for me until I did a clean reinstall of Catalina and then the permissions window finally appeared and I was able to say "yeah, let Dropbox do its thing." Really bad user experience, if I knew I'd have to do a clean reinstall, I would've waited to upgrade.