buster, light-locker 1.8.0-3 how to reproduce: 1 under xfce, lock the screen; 2 the display turned off 3 when I need to use it, pressing keyboard or moving mouse will not turn the screen back on.
I have this problem on both my laptop(which has a single integrated intel card and my desktop which has an integraed intel card and an additional ati card). Workarounds for me: 1 Blindly type my password and hit enter and the screen will be back on with unlocked desktop - not ideal but usable. 2 hit ctrl-alt-f1(actually, any of f1-f7) will turn the screen back on and then press ctrl-alt-f8 will show me the lock screen and I can type my password there and unlock. Hopefully this little problem can be solved. Thanks.