I have the same issue but I found a different workaround without having to resort to the Ctrl-Alt-F2 then back to Ctrl-Alt-F1 trick for the login screen to appear :
https://askubuntu.com/questions/1389869/multiple-monitors-black-screen-with-blinking-cursor-and-gnome-desktop-login-on
I have to ensure that the "Primary Display" is set to the laptop monitor instead of the external monitor connected via HDMI.
I have the same issue but I found a different workaround without having to resort to the Ctrl-Alt-F2 then back to Ctrl-Alt-F1 trick for the login screen to appear :
https:/ /askubuntu. com/questions/ 1389869/ multiple- monitors- black-screen- with-blinking- cursor- and-gnome- desktop- login-on
I have to ensure that the "Primary Display" is set to the laptop monitor instead of the external monitor connected via HDMI.