MY SYSTEM 

Linux/KDE Plasma: KDE Neon 20.04
KDE Plasma Version: 5.21.4
KDE Frameworks Version: 5.80.0
Qt Version: 5.15.2

SUMMARY

I have set "Double click" for open my files and folders. Sometimes, in my desktop, when i go to do double click for open my files, it don't work and nothing happens. Other times yes work.

If i use Dolphin, it always work.

When it don't work, i go to log my system (/var/log/syslog) and it show this:

kwin_x11[1504]: file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null
kwin_x11[1504]: message repeated 2 times: [ file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null]
kwin_x11[1504]: QPainter::begin: Paint device returned engine == 0, type: 3
rtkit-daemon[1396]: Supervising 5 threads of 2 processes of 1 users.
rtkit-daemon[1396]: Supervising 5 threads of 2 processes of 1 users.
plasmashell[1578]: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/main.qml:464: TypeError: Cannot read property 'length' of undefined
systemd[1379]: Started Telegram Desktop.
plasmashell[1578]: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/Task.qml:379: Unable to assign [undefined] to QString
kwin_x11[1504]: file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null
kwin_x11[1504]: message repeated 2 times: [ file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null]
kded5[1500]: Registering ":1.64/StatusNotifierItem" to system tray
kwin_x11[1504]: file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null
kwin_x11[1504]: QPainter::begin: Paint device returned engine == 0, type: 3
plasmashell[1578]: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/main.qml:464: TypeError: Cannot read property 'length' of undefined
systemd[1379]: Started Konsole - Terminal.
kwin_x11[1504]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 56621, resource id: 39846082, major code: 18 (ChangeProperty), minor code: 0
plasmashell[1578]: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/Task.qml:379: Unable to assign [undefined] to QString
kwin_x11[1504]: file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null
kwin_x11[1504]: message repeated 4 times: [ file:///usr/share/kwin/aurorae/MenuButton.qml:11: TypeError: Cannot read property 'closeOnDoubleClickOnMenu' of null]
kwin_x11[1504]: QPainter::begin: Paint device returned engine == 0, type: 3