preferences window won't appear
I installed f.lux, but no "preference" window will appear so that I can type in my wake up time, etc.
Have you checked out Preferences>Users & Groups>Login Items ?
I have a similar problem. I click on it and nothing happens. I haven't been able to set my times up or location because of this. Any
I also have the same bug on Mac OS Catalina; it only works when opening the application afresh, but stops working when it has been running for a longer period.