Paul - I have noticed something: If I clap on comments from the main page of the article (ie in the comment sidebar that appears on the right hand side) the claps remain. If I clap from the full screen page of a comment, they don't. So now I try to make a point of going back to the original article page, opening the comment sidebar, scrolling through, etc. It's annoying and time consuming, but it does work (for me at least).

I think my claps remain for your articles. Please let me know if they don't. I've clapped this one fifty times.