Maybe this is how it should be, but:
It works great when the url is e.g. domain.com/mypostname/
The enveloppe icon shows, the text shows and the opoup and send email works.
On my front page where the latest newests post are it does not show at all.
I just use the shortcode [WPRError], but tried the other options with the same result.
So it only shows up and works when the post is alone and single in the browser tab