Hello everyone,
here's my issue.
After a reboot, notify-send test takes a minute or so to give back control of the terminal. I found out about this issue while trying to figure out why some applications in my PC were freezing or hanging.
I have disabled the notifications in Notification Settings -> untick Show application and system notifications. If I tick it, the notification is shown promptly and correctly.
I found out that removing .config/plasma* (or rather, moving those files elsewhere), rebooting, disabling notifications, and rebooting again, solves the issue. Obviously, this is annoying because I lose a lot of Plasma settings. Nonetheless, the fix is only temporary: after some use of PC the issue reappears. However, I can't seem to identify the cause of the issue.

System information:
Recently installed Kubuntu 18.04.2 64-bit
KDE Plasma v5.12.7
KDE Frameworks v5.44.0
Qt v5.9.5
Kernel version: 4.18.0-15-generic
4×Intel Core i3-6100 CPU @ 3.70GHz
7.6 GiB RAM

Here are the .config/plasma* files:

Code: Select all

$ cd .config
$ ls plasma*
plasma-localerc  plasma-nm  plasma-org.kde.plasma.desktop-appletsrc  plasmashellrc

$ cat plasma-localerc
[Formats]
LANG=it_IT.UTF-8

$ cat plasma-nm
[General]
ManageVirtualConnections=false
UnlockModemOnDetection=true

$ cat plasmashellrc
[PlasmaRunnerManager]
LaunchCounts=1 services_kcmsmserver.desktop,2 services_khotkeys.desktop,2 services_org.kde.kamoso.desktop,1 services_grub-customizer.desktop,1 services_componentchooser.desktop,3 services_keys.desktop,1 services_kamera.desktop,5 services_autostart.desktop,1 services_firefox.desktop,1 services_dbeaver.desktop
pluginWhiteList=services,places,desktopsessions,PowerDevil,shell,bookmarks,recentdocuments,locations,baloosearch

[PlasmaViews][Panel 2][Horizontal1920]
thickness=36

[ScreenConnectors]
0=HDMI-2

[Updates]
performed=/usr/share/plasma/shells/org.kde.plasma.desktop/contents/updates/obsolete_kickoffrc.js

$ cat plasma-org.kde.plasma.desktop-appletsrc
[ActionPlugins][0]
MidButton;NoModifier=org.kde.paste
RightButton;NoModifier=org.kde.contextmenu
wheel:Vertical;NoModifier=org.kde.switchdesktop

[ActionPlugins][1]
RightButton;NoModifier=org.kde.contextmenu

[AppletGlobals][org.kde.plasma.notifications]
popupPosition=0

[Containments][1]
activityId=00fe3abe-ac08-4864-9487-ce27eceda9c9
formfactor=0
immutability=1
lastScreen=0
location=0
plugin=org.kde.plasma.folder
wallpaperplugin=org.kde.image

[Containments][1][Configuration]
PreloadWeight=18

[Containments][1][General]
ToolBoxButtonState=topright
ToolBoxButtonX=1890

[Containments][2]
activityId=
formfactor=2
immutability=1
lastScreen=0
location=4
plugin=org.kde.panel
wallpaperplugin=org.kde.image

[Containments][2][Applets][3]
immutability=1
plugin=org.kde.plasma.kickoff

[Containments][2][Applets][3][Configuration]
PreloadWeight=92

[Containments][2][Applets][3][Configuration][Configuration/General]
showAppsByName=true

[Containments][2][Applets][3][Configuration][General]
favorites=preferred://browser,org.kde.discover.desktop,org.kde.kontact.desktop,org.kde.kate.desktop,libreoffice-startcenter.desktop,org.kde.dolphin.desktop,org.kde.ksysguard.desktop,systemsettings.desktop,org.kde.konsole.desktop
favoritesPortedToKAstats=true
showAppsByName=true

[Containments][2][Applets][3][Configuration][Shortcuts]
global=Alt+F1

[Containments][2][Applets][3][Shortcuts]
global=Alt+F1

[Containments][2][Applets][4]
immutability=1
plugin=org.kde.plasma.pager

[Containments][2][Applets][4][Configuration]
PreloadWeight=18

[Containments][2][Applets][5]
immutability=1
plugin=org.kde.plasma.taskmanager

[Containments][2][Applets][5][Configuration]
PreloadWeight=18

[Containments][2][Applets][5][Configuration][ConfigDialog]
DialogHeight=540
DialogWidth=720

[Containments][2][Applets][5][Configuration][General]
highlightWindows=true
launchers=applications:flameshot.desktop,applications:org.kde.dolphin.desktop,applications:org.kde.kate.desktop,applications:opera.desktop,applications:telegramdesktop.desktop

[Containments][2][Applets][6]
immutability=1
plugin=org.kde.plasma.systemtray

[Containments][2][Applets][6][Configuration]
PreloadWeight=48
SystrayContainmentId=7

[Containments][2][Applets][8]
immutability=1
plugin=org.kde.plasma.digitalclock

[Containments][2][Applets][8][Configuration]
PreloadWeight=18

[Containments][2][Applets][9]
immutability=1
plugin=org.kde.plasma.showdesktop

[Containments][2][Applets][9][Configuration]
PreloadWeight=18

[Containments][2][ConfigDialog]
DialogHeight=84
DialogWidth=1920

[Containments][2][Configuration]
PreloadWeight=18

[Containments][2][General]
AppletOrder=3;4;5;6;8;9

[Containments][7]
activityId=
formfactor=2
immutability=1
lastScreen=0
location=4
plugin=org.kde.plasma.private.systemtray
wallpaperplugin=org.kde.image

[Containments][7][Applets][10]
immutability=1
plugin=org.kde.discovernotifier

[Containments][7][Applets][10][Configuration]
PreloadWeight=28

[Containments][7][Applets][11]
immutability=1
plugin=org.kde.plasma.clipboard

[Containments][7][Applets][11][Configuration]
PreloadWeight=18

[Containments][7][Applets][12]
immutability=1
plugin=org.kde.plasma.vault

[Containments][7][Applets][12][Configuration]
PreloadWeight=18

[Containments][7][Applets][13]
immutability=1
plugin=org.kde.kdeconnect

[Containments][7][Applets][13][Configuration]
PreloadWeight=18

[Containments][7][Applets][14]
immutability=1
plugin=org.kde.plasma.devicenotifier

[Containments][7][Applets][14][Configuration]
PreloadWeight=18

[Containments][7][Applets][15]
immutability=1
plugin=org.kde.plasma.notifications

[Containments][7][Applets][15][Configuration]
PreloadWeight=18

[Containments][7][Applets][15][Configuration][ConfigDialog]
DialogHeight=540
DialogWidth=720

[Containments][7][Applets][15][Configuration][General]
showHistory=false
showNotifications=false

[Containments][7][Applets][16]
immutability=1
plugin=org.kde.plasma.printmanager

[Containments][7][Applets][16][Configuration]
PreloadWeight=18

[Containments][7][Applets][17]
immutability=1
plugin=org.kde.plasma.volume

[Containments][7][Applets][17][Configuration]
PreloadWeight=18

[Containments][7][Applets][18]
immutability=1
plugin=org.kde.plasma.battery

[Containments][7][Applets][18][Configuration]
PreloadWeight=18

[Containments][7][Applets][19]
immutability=1
plugin=org.kde.plasma.networkmanagement

[Containments][7][Applets][19][Configuration]
PreloadWeight=18

[Containments][7][ConfigDialog]
DialogHeight=540
DialogWidth=720

[Containments][7][Configuration]
PreloadWeight=18

[Containments][7][General]
extraItems=org.kde.plasma.vault,org.kde.kdeconnect,org.kde.plasma.networkmanagement,org.kde.plasma.notifications,org.kde.plasma.devicenotifier,org.kde.discovernotifier,org.kde.plasma.mediacontroller,org.kde.plasma.battery,org.kde.plasma.clipboard,org.kde.plasma.volume,org.kde.plasma.printmanager
hiddenItems=org.kde.kdeconnect,org.kde.plasma.vault,org.kde.plasma.notifications
knownItems=org.kde.plasma.vault,org.kde.plasma.bluetooth,org.kde.kdeconnect,org.kde.plasma.networkmanagement,org.kde.plasma.notifications,org.kde.plasma.devicenotifier,org.kde.discovernotifier,org.kde.plasma.mediacontroller,org.kde.plasma.battery,org.kde.plasma.clipboard,org.kde.plasma.volume,org.kde.plasma.printmanager

[General]
immutability=1

[ScreenMapping]
itemsOnDisabledScreens=
screenMapping=desktop:0-picture_2019-03-01_00-12-33.jpg,0,desktop:/trash.desktop,0,desktop:/Home.desktop,0



I hope someone can help me. Thanks!