Comment 12 for bug 1812594

You were spot on apt-ghetto.

`apt-cache policy` read 0.54.2 & no I didn't have -proposed enabled
I copied the two desktop.conf you mentioned so will look at that later..
I've added -proposed; `apt update; apt full-upgrade`
logout, login.
// GRRR (i logged out & logged in on real machine, not VM)
// clean up the mess i made...
apt-cache policy now reads 0.54.3; but i'll reboot VM before I continue

apt-cache policy reads 0.54.3 (bionic-proposed/universe) installed
0.54.2 (bionic/universe)

(no diff between desktop.conf's found in $HOME/.config/lxsession/Lubuntu/)
grep of $HOME version results in "lock manager/command=lxlock"
// please note I'm typing, and not copy/pasting..
diff of /etc/..desktop.conf shows diffference!
$diff desktop.conf-normal_etc_xdg_lxsession /etc/xdg/lxsession/Lubuntu/desktop.conf
> lock_manager/command=light-locker-command -l
>
$ grep lock /etc/xdg/lxsession/Lubuntu/desktop.conf
lock_manager/command=light-locker-command -l
logged out; logged back in..

rm ~/.config/lxsession/Lubuntu/desktop.conf
logout
login
file ~/.config/lxsession/Lubuntu/desktop.conf (ASCII text)

CTRL+ALT+L & screen is black....

move mouse & I'm at login/greeter
my usual password & i'm back at terminal

Results @wxl no doubt got... (finally)