I opened a bug with KDE, because copy & paste from folderview desktop containment doesn’t work with keyboard shortcuts.
To reproduce show desktop (folderview) and try to copy/cut an item by keyboard shortcuts and paste it elsewhere.
However, the KDE devs could not reproduce this issue, so I tried with Plasma 5.4.2 on Kubuntu in a VM and it worked.
Thus I think it might be a Netrunner issue.
UPDATE: Somehow solved with Plasma updated to 5.6.1.
Yes this was fixed in Plasma 5.6