I am using Linux Mint 18.3 KDE Edition with KDE Plasma 5.8.9. As a file manager, I use the default "File" application but the issue I have may also be found with Thunar or Dolphin.
If I use the copy shortcut Ctrl+C for a file on the desktop (folder mode), then I realized I cannot copy it in a folder of the file manager. Both "Ctrl+V" and right-click/paste do not work.
However, if I copy the file using the shortcut Ctrl+Shift+C then I can paste it both ways.
I am puzzled with this behaviour as I cannot find any definition of the Ctrl+Shift+C shortcut in KDE... I know this is the default copy shortcut for konsole (which I installed) but I do not understand the link here...