#945926 KDE on Debian 10.2, dual (HDMI & VGA) monitors: Can no longer login through lock screen to same session after disconnecting and reconnecting HDMI monitor

Package:
kde-plasma-desktop
Source:
meta-kde
Description:
KDE Plasma Desktop and minimal set of applications
Submitter:
Judah Richardson
Date:
2019-12-01 07:45:06 UTC
Severity:
normal
#945926#5
Date:
2019-12-01 07:42:45 UTC
From:
To:
Debian Release: 10.2
uname -a: Linux 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u2 (2019-11-11)
x86_64 GNU/Linux

Introduction: I have a Debian 10 machine running KDE, described fully
(config, specs, software, etc.) here
<https://github.com/jdrch/Hardware/blob/master/Dell%20OptiPlex%20390-1%20SFF.md>.
I had the screen locked using CTRL+ALT+L, which makes the lock screen login
dialog show up on both monitors when the mouse is clicked.

Bug: I recently temporarily disconnected the HDMI monitor from the Debian
10 machine's HDMI port so I could connect the monitor to another machine.
Upon reconnecting the HDMI monitor, the monitor shows a blank screen with a
static cursor. The VGA monitor still shows the lock screen on mouse click,
but when I click the password field to enter my password, no cursor appears
and when I type no characters appear, either.

Expected behavior: I should be able to click the password field and log
back into the desktop session