Bug in software, not sufficient material

Hello!

I was just playing a game in which in the final position I had a knight and king, vs my opponents two pawns and king. My opponent runs out of time and I expect the win. However, the game is drawn by "not sufficient material". This is clearly wrong since my opponent could promote to a bishop and then put his king in the corner, a position that would lead to mate.

Best regards,

You have to be able to forceate without opponents help

Force*

That is not true

But you would not be able to force that position you describe with a King and a Knight only

You don't have to force it. Your opponent can play badly 

That is correct, the site does not use the FIDE ruling of if mate is possible by any series of legal moves, it primarily only looks at the material the side with time has. The rules used here are closer to the USCF rules, where mate has to be forceable.

So, K+B, K+N, and K+N+N is considered insufficient material. I believe in the latter case the site gives the win if the other side also has a pawn; that wasn't the case in the past, but it is now more aligned with FIDE and USCF rules.

https://support.chess.com/customer/en/portal/articles/1444798-how-do-i-claim-a-draw-

The end of that article explains it.

Does it mean that a player who has been correctly forced into Stamma´s mate should refuse to move and run out of time, and with a forced mate in one on board would be entitled to claim draw when time is ended?

I'm sure there are situations where there is a forced mate on the board, where timing out by the losing side side would encounter insufficient material. The site might be checking for forced mates on those, but I'm not sure.