I cannot get the title bar to hide on specific monitor, if it isn't the 'Main Display' on my PC. Another monitor works if it is not the main display. I have tried f11, alt-enter, but it always appears windowed on the display. If I mark the display as the 'Main Display' it instantly begins to work. I cannot use this as my main display in my setup and would like to fix this if possible.
Enable “Displays have separate Spaces”
This is the #1 cause of the problem.
Go to:
System Settings → Desktop & Dock → Mission Control → “Displays have separate Spaces” → ON
Then log out and back in (or reboot).
Without this enabled, macOS cannot create a “fullscreen space” on a secondary monitor, so it forces the app into windowed mode.
Enable “Displays have separate Spaces”
This is the #1 cause of the problem.
Go to:
System Settings → Desktop & Dock → Mission Control → “Displays have separate Spaces” → ON
Then log out and back in (or reboot).
Without this enabled, macOS cannot create a “fullscreen space” on a secondary monitor, so it forces the app into windowed mode.
Title bar won't hide in fullscreen on specific monitor if not marked as 'Main Display'
