BST worked well before I have updated from 10.12 to Catalina. When I use the commands in the header everything is ok. But when I move the window to the top or to the side of the screen nothing happened. Any idea what could be the reason?
Have you already tried enabling this?
Otherwise maybe try to restart your System once.
There is also a rare bug on Catalina, where apparently some few systems require the input monitoring permission in System Preferences -> Security and Privacy -> Privacy -> Input Monitoring (However I haven't seen that myself yet)
Oh, and could you explain what you mean by "commands in the header'?