Here's the link to the game:
http://www.chess.com/livechess/game?id=609229069
As you can see, it should have been three-fold. But for some reason, this wasn't triggered.
It doesn't trigger automatically. Just like in OTB, you have to claim it. Think there's a button or something you have to press.
If you want to claim a draw by threefold repetition or 50 move rule , you press the "offer draw" button. If the conditions are valid the server declares an immediate draw.
Here's the link to the game:
http://www.chess.com/livechess/game?id=609229069
As you can see, it should have been three-fold. But for some reason, this wasn't triggered.