Bug
When copy and pasting, you are only able to paste to a new/empty line using the keyboard shortcut and not the right click paste. This is reproducible on the demo site on Chrome Stable 64

Able to paste using right click.
I think the problem is that the right-click menu pop-up lose the selection.
It works fine on [email protected] & [email protected]

I'm unable to reproduce this, testing with OSX and Windows in multiple browsers. I'll close this issue, but if you provide more info on how to reproduce, we're happy to reopen it.
Most helpful comment
I think the problem is that the right-click menu pop-up lose the selection.