The copy/paste functionality when using the blueprint editor is broken or at least works erratically in 4.11 on Linux. Using either ctrl-C or the right mouse to select copy does nothing, or if it does, you can’t paste what you just copied. The material editor also has issues on the same point.
A workaround is to copy/paste anything in another window, like a text editor, and then it should start working again. That worked for me.
My suspicion is that the editor sees something in the clipboard that it can’t handle and hangs on processing anything else.
Thanks go to whammy for sharing this tip with me on the #UE4Linux IRC channel.