In the page editor, when you copy a block, click on an empty area of the navigator (below all other blocks) and then paste (using e.g. Cmd+V), this appends the pasted block. When doing this in the site editor, it does nothing.
Just following up on this from the other thread. @Louis, I know you have a lot on your plate right now with components and other features/fixes. When you have time, please comment on this as per @Araminta’s message.