ShareThis Chicklets are missing

All of a sudden the sharethis chicklets are no longer appearing on any of my sites. They are in two different hosting environments as well as on my mac at home so I am guessing the issue is not the environment.

I have noticed when speed testing some pages recently that the sharethis chicklets were taking a long time to download, now they don't appear at all. If I view source, instead of the buttons I see

<div class="sharethis-buttons">
  <div class="sharethis-wrapper">
    <span st_url="http://mydomain.com/content/home" st_title="Home" class="st_twitter"></span>
    <span st_url="http://mydomain.com/content/home" st_title="Home" class="st_facebook"></span>
    <span st_url="http://mydomain.com/content/home" st_title="Home" class="st_sharethis"></span>
    <span st_url="http://mydomain.com/content/home" st_title="Home" class="st_plusone"></span>
    <span st_url="http://mydomain.com/content/home" st_title="Home" class="st_fblike"></span>
    <script type='text/javascript'>
      var switchTo5x=true;
    </script>
    <script type='text/javascript' src='http://w.sharethis.com/button/buttons.js'>
    </script>
    <script type='text/javascript'>stLight.options({publisher:'dr-bfc61fcb-4345-7280-cc8d-96884eb83209'});</script>
  </div>
</div>

I have never looked at the code for the chicklets before so I am not sure if this is what is supposed to be there.

They were working a couple of days ago, I have altered themes on a couple of sites, on others nothing has changed. Does anyone know what could be happening here?