I have Plasma on Fedora 26. I use a laptop and my settings in Energy Saving are set to switch screen off after 10 minutes. Normally this works fine. The screen duly switches of after 10 minutes; autolocking (after 5 minutes) does not affect it.

But when I use the manual key (Ctrl+Alt+L by default) to lock the system, the lock screen stays on indefinitely. It never switches off.

How can I tweak something so that the screen would turn off in that case too? Thanks!