When you select the text and click the right mouse button (for copy), the selection is lost. Usually I do not use a mouse, but only the keyboard.
This was previously not happening (but some updates - new versions).
Of course this is not a big problem, but could be annoying…
no such problem for me. Tested on Notepad++: v6.8.3 @ Windows 7 x64.
Maybe try also on another PC, mouse, … . Or try to be more specific about your release, programming language, …? Provide more info how to reproduce this issue.