Unable to paste external copied text into editor

I copy a piece of source from an example from StackOverflow, try to paste it on the Java editor (either via CTRL+V or with right click --> paste), and all I get pasted is the last text I selected and CTRL+C'ed from Netbeans editor itself.

If I go to whatever random text editor (for instance, Notepad++) and try the same operation (even without having to repeat the copy action), the proper text gets pasted (I mean: not the invalid, prior selection I made inside Netbeans, but the piece of code I copied from StackOverflow gets pasted).