I have used Linux, dozens of distros, for over ten years and have used
Kubuntu for the past four and have never had a single issue with copy, cut
or paste. I am a heavy user of cut and paste. That is not to say there isn't
a problem, but to me it means that it is likely an issue with your
technique, a particular application that I don't use or with hardware and
not with Ubuntu per se. I have hundreds of applications installed, but there
are some applications that I won't use, so I may just be lucky. I cut and
paste in graphics, multimedia, text and files every day.