The Computer in chess.com does not know the three fold repetition. Look at this game below which I played with the computer. (I was White)

I hope chess.com will fix this problem.

There's not really anything to fix.  The games against LCP aren't recorded anywhere onsite.  You know it is a draw, and you can claim it by simply starting a new game.  That's how I've always seen it, anyway.

You have to click Draw and then it should come up as a Claim Draw button!

Hope that helps :)