After doing conversion of 20.04 on my RPI 4 B to run Lubuntu desktop, I'm still able to login via mosh/ssh, but when I try entering my password in the GUI login screen, it says Login Failed.
I have exactly the same problem. I am able to login in tty2 or other terminals but not in the GUI. I also tried changing the password but the result is the same. I am using 20.04 on RPI 4B to run Lubuntu Desktop.
After doing conversion of 20.04 on my RPI 4 B to run Lubuntu desktop, I'm still able to login via mosh/ssh, but when I try entering my password in the GUI login screen, it says
Login Failed
.