Well, had the same problems, and after fighting it for a while, I realized that there's something wrong on the index.html file that C2 generates when you export it for Kongregate. I've looked through the console in Chrome, and it was pointing to an http that retrieved a GET error.
So open your index.html in an editor an replace this line:
<script src="//www.kongregate.com/javascripts/kongregate_api.js"></script>
To this one:
<script src="https://ssl.kongcdn.com/javascripts/kongregate_api.js"></script>
That should do the trick (Y)