Copy-paste bug: cannot copy-paste library symbols in Symbol Editor

I cannot replicate the copy-paste process in the video (Linx) on Mac OS X. What I’m trying to do is to create a copy of an existing symbol and modify it. Unfortunately every time I try to paste the part into a new library, I get ‘Nothing to paste’ error.

Are you on the same KiCad version as shown in the video?
Plus do you really expect us to watch a 5 minute video just to know what you might have tried? Give the step by step explanation of what you did to get to the error message!