There are times when I have to enter my password multiple times to get past the screen locker. When I enter a bad password the response is immediate that I have done so. When I enter a correct password it will blank the screens (I have 4 of them) for a few seconds and then return to the lock screen. Eventually, it will accept the password and life goes on.

I have yet to identify the exact alchemy that causes the problem. Sometimes it works perfectly and other times it does not. When it does not I am always eventually successful. 

If there is something that I can do to aid in troubleshooting this erratic bug a pointer in the right direction will likely be all I need. 

$ uname -a
Linux lemix 4.13.0-18-generic #21-Ubuntu SMP Tue Nov 21 17:01:50 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

$ apt list --installed | grep libqt5concurrent5

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

libqt5concurrent5/artful,now 5.9.1+dfsg-10ubuntu1 amd64 [installed]

$ apt list --installed | grep plasma

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

kdeconnect-plasma/artful,now 1.0.3-0ubuntu2 amd64 [installed]
kdeplasma-addons-data/artful,artful,now 4:5.10.5-0ubuntu2 all [installed]
libkf5plasma-dev/artful,now 5.38.0-0ubuntu1 amd64 [installed]
libkf5plasma5/artful,now 5.38.0-0ubuntu1 amd64 [installed]
libkf5plasmaquick5/artful,now 5.38.0-0ubuntu1 amd64 [installed]
libplasma-geolocation-interface5/artful,now 4:5.10.5-0ubuntu1 amd64 [installed]
libplasma3/artful,now 4:4.14.34-0ubuntu2 amd64 [installed]
plasma-dataengines-addons/artful,now 4:5.10.5-0ubuntu2 amd64 [installed]
plasma-desktop/artful,now 4:5.10.5-0ubuntu1 amd64 [installed]
plasma-desktop-data/artful,artful,now 4:5.10.5-0ubuntu1 all [installed]
plasma-discover/artful,now 5.10.5-0ubuntu1 amd64 [installed]
plasma-discover-common/artful,artful,now 5.10.5-0ubuntu1 all [installed]
plasma-framework/artful,now 5.38.0-0ubuntu1 amd64 [installed]
plasma-integration/artful,now 5.10.5-0ubuntu1 amd64 [installed]
plasma-look-and-feel-org-kde-breezedark-desktop/artful,artful,now 4:5.10.5-0ubuntu1 all [installed]
plasma-nm/artful,now 4:5.10.5-0ubuntu1 amd64 [installed]
plasma-pa/artful,now 4:5.10.5-0ubuntu1 amd64 [installed]
plasma-runners-addons/artful,now 4:5.10.5-0ubuntu2 amd64 [installed]
plasma-scriptengine-javascript/artful,now 4:17.04.3-0ubuntu1 amd64 [installed]
plasma-wallpapers-addons/artful,now 4:5.10.5-0ubuntu2 amd64 [installed]
plasma-widgets-addons/artful,now 4:5.10.5-0ubuntu2 amd64 [installed]
plasma-workspace/artful,now 4:5.10.5-0ubuntu1 amd64 [installed]