This can be fixed by installing
kde-plasma-desktop via the ppa
% sudo add-apt-repository ppa:kubuntu-ppa/backports
% sudo apt update
% sudo apt install kde-plasma-desktop
When prompted to use Choose
Run an update post-install
% sudo apt update
Reboot the machine and log back into Ubuntu.
When you log in, try your regular desktop. When typing in password, gear will show on bottom right of screen, click on this to see desktop options. The standard for Ubuntu 20.04 Gnome is
If you have issues logging into the desktop, you can type
ctrl-alt-F3 to get to a console to troubleshoot. Note that it may be required to do another
sudo apt-update after logging back in, as this is how I had to resolve login issues, although I did not do the update after the initial install.
That should get this right click issue as well as many other KDE app issues resolved under Gnome. I noticed that all the apps now look correct, have proper context menu functionality and function much better in general.
My experience so far with initially installing
kubuntu-desktop on the same machine as my Gnome Ubuntu has been bad as it broke my regular Ubuntu Gnome desktop. I'm now having to look at reverting back to the ZFS snapshot before the change as it pooched a bunch of functionality in Gnome. I hope to try again with
kde-plasma-desktop after I survive that process (fingers crossed).
Was able to revert the base system to before
kubuntu-desktop was installed and subsequently installed
kde-plasma-desktop. I can confirm that
kde-plasma-desktop installation fixes issues with right click issues in KDE Apps. Note that
kde-plasma-desktop itself was very large and the subsequent
apt update took down a ton more changes. However, my Gnome desktop seems to be working well now alongside the KDE Apps.