I use this theme http://themewich.com/aware/
And the buttons appear when any of the portfolio thumbnails are expanded. Wouldn't be the end of the world if they were there, and worked - but upon using them, you don't share the portfolio object but the homepage URL itself, despite using the title of the portfolio object.
Most of all, I would want to hide them completely on the frontpage, but unchecked "Frontpage" and "Excerpts" doesn't do the trick. This theme uses a static page as homepage. Making it possible to hide the buttons on a specific would perhaps have worked things out?
I really like this plugin, but I can't use it if this isn't sorted out.