Deprecated:
OnzeMenu is not that customizable but I hope it will continue to improve.
This is most likely due to missing plasma-widgets-addons
package on your system.
You can install this using sudo apt install plasma-widgets-addons
on Ubuntu / Debian Distros or sudo pacman -S kdeplasma-addons
on Arch based distro.
If you have any other distro then please search for the package name for your distro.
This can be due to various reasons:
You can create an issue if you think it's due to a KDE update or it's not mentioned above.
git clone https://github.com/prateekmedia/Menu11.git ~/.local/share/plasma/plasmoids/menu11;
kquitapp5 plasmashell || killall plasmashell && kstart5 plasmashell;