I have many different issues to the clipboard that may or may not be related. I will try to list all of the symptoms below, but in general, in the last week or two copy/paste has stopped working on all my computers. I had KDE neon installed on 4 machines. Because copy/paste had become so unusable in the last week I wiped 3 of the machines yesterday and installed Kubuntu 20.04. The issues on Kubuntu appear to be identical.

• Most of the time copy does not copy. This is true whether it's Ctrl+C, Right-click copy, or Copy toolbar button in Dolphin. I know this because when I look at the clipboard pop out from the system tray it does not have an entry for what I tried to copy.
  
• Although I can't tell that Ctrl+C is doing anything when the clipboard shows empty, I can tell that Cut Ctrl-X is doing something, because the text disappears. However, looking in the clipboard it is missing and doesn't paste. This could be more troubling because the thing you "cut" is now gone. I have had success with Undo or Ctrl+Z to get text back.
• Sometimes the top entry in the clipboard is correct indicating that copy did work, but paste still doesn't paste anything.
  
• Often the top entry in the clipboard is empty data. Often if I try to delete the empty entry it is replaced immediatly with another empty entry.

I appreciate the great help from the community. I am happy to get any logs or do any testing required.

I am also having copy/paste problems & I posted a question here:

viewtopic.php?f=15&t=168619

Did you ever find a fix for this?