I know this type of question has been asked a few times but each of the puzzles in the answers are solved by engines. For example Plaskett’s puzzle and other common ones such as Mitrofanov deflection and Mario Matous’ mate in 13 can be seen by matefinders easily. Are there any puzzles that truly stump engines?
Usually, swindles and those sort of puzzles stump engines because practically the best chance of winning is variation A, but the computer prefers variation B because it has a different calculation system to us. Those are usually the hardest for computers and they usually get them wrong, even if it is technically correct.