I'd like to go to a terminal so I can kill processes jamming my windowing session. (I would then return with CTRL-ALT-F7.) But CTRL-ALT-F1 just locks the screen; no terminal.
CTRL-ALT-Fn-F1 similarly does not work.
What am I doing wrong? How do I get the effect of CTRL-ALT-F1?
(This is a Dell Inspiron 15 7000 Gaming with Ubuntu 18.04)