I read several follow-ups at different places. To the best of my knowledge, the rules break down as this:
After 50 moves with no pawn being moved or a piece being captured, a draw may be claimed.
After 75 moves under the same conditions, the game is a draw regardless of a claim being made.
Didn't they make a change to the repetition rules as well?
That position, and several others, repeated over and over again, ad infinitum. Just clicking the "Offer Draw" button after every move should have worked eventually.
The last pawn move/capture was made at move 31, and no further pawn move or piece exchange was made all the way to the end at move 272. My arithmetic might be a bit rusty, but I think that's at least 50 moves.
Oh, and one thing I learned from yesterday's marathon WCC game, FIDE rules state that after 75 moves without a pawn move or piece capture, the game is a draw whether it is claimed or not.
Okay, I looked at the game. There were five distinct positions after Black's moves 31 to the end. Each was repeated dozens of times.
There were an additional four positions after each of White's moves. These, too, were repeated ad nauseum.
Where were you following yesterday's WCC game? On the official site, Peter Svidler confessed uncertainty whether the current FIDE rule was 50 or 75 moves. Someone he trusted verified that it was 50.