How can I remove the black space in full screen mode?

Wait... I just noticed that your profile says MacBook Pro 14".

I am thinking that this behaviour must be associated with the "notch"... I don't have one of those macs to test, but if the whole interface were to go all the way up, you'd end with a cut in the center, where the notch is. I am inclined to believe that this is not in error, and in fact it is deliberate.

Otherwise you'd get something like this:

Try deleting FCP preferences.

To delete preferences, hold down command and option while starting FCP X and click Delete Preferences. The application will start in a default state, and open an “Untitled” library.

Reopen the library you were working on, set the preferences the way you like them, and try again.

What app is this?

I recognize the Final Cut Pro interface.

Does this happen with just FCP or with all applications?

What OS version? What mac? What display?

👍 the Notch