Unsuccessfully pasting clears the buffer under certain circumstances
If you "cut" a certain file or a folder, and then paste it in a location to which pasting is not possible (like pasting cut folder into itself), Nautilus forgets about the cut objects, and you can't paste them again after that, even though they are still in their original location. If you do the same thing with the "Copy" action, it doesn't occur. Personally, this behavior is very confusing and annoying, since I expect to be able to try to paste into a different location again, but unable to without selecting and cutting the needed files again. Nautilus Version: 40.2
Edited by Peter Eisenmann