Using KDE Neon with Plasma 5.11.5 on a Lenovo ThinkPad T470S with a ThinkPad USB-C Dock and an external monitor. A plasma panel is on the main monitor (on the laptop) and its visibility is set to the default "Always Visible". When I use only the laptop screen, the panel behaves as expected, i.e. windows are not allowed to hover or go below the panel. However, when I connect the USB-C dock and the second monitor comes into play, suddenly the panel behaves as if its visibility has been set to "Windows Go Below". Note that in the "More Settings" of the panel the visibility is still set to "Always Visible". A simple workaround to make the panel behave as expected is to go the "More Settings" of the panel, choose some other visibility setting before choosing again the "Always Visible" setting.
Same issue exists with a simpler setup on a second PC with Plasma 12.1. No docking station here. As long as I connect an external monitor, disconnect it and reconnect it, I experience this bug.
please post your ~/.config/plasmashellrc
Here it is the ~/.config/plasmashellrc: [DownloadDialog Settings] Height 1440=522 Width 2560=700 [PlasmaRunnerManager] LaunchCounts=1 services_about-distro.desktop pluginWhiteList=services,places,desktopsessions,PowerDevil,shell,bookmarks,recentdocuments,locations,baloosearch [PlasmaViews][Panel 2] alignment=1 panelVisibility=0 [PlasmaViews][Panel 2][Horizontal1920] thickness=54 [ScreenConnectors] 0=eDP-1 1=DP-1-2 [Updates] performed=/usr/share/plasma/shells/org.kde.plasma.desktop/contents/updates/obsolete_kickoffrc.js
This bug is one of the symptoms also described here https://bugs.kde.org/show_bug.cgi?id=390597
*** This bug has been marked as a duplicate of bug 390597 ***