Positions chess engines don't understand
When watching the WC games, I've seen it happen that a move wasn't considered as a top move by the engine, but once played the engine realizes it's actually crushing. Something about the heuristics used to prune the vast search space can make it miss sacrifices or seemingly sub-optimal moves that temporarily weakens the perceived position but has a huge payoff in the end. But humans find them. Of course, given enough time and depth the engine will eventually circle back and try the move. But it has no intuition.Also, an engine without an endgame tablebase can be pretty stupid. There are certain rules one can deduct when there are few pieces left, but a min/max engine will search forever, not knowing the patterns.