I've set up a dual boot with Ubuntu.
I've set up a dual boot with Ubuntu.
Did you allow the installer to download and apply updates? If not, it’s probably just a GNOME issue—something that occurred to me too—and can be resolved by installing updates. Usually you press ctrl+alt+F2 or ctrl+alt+F1 to enter the text console, log in and run "sudo apt update", "sudo apt -y dist-upgrade" and then "sudo reboot". This refreshes everything and should fix the problem.
Use the specified key combination to return to the text-console.