Both JACK 5's double dummy solver and the Linux double-dummy solver claim that North or South can make twelve tricks in notrump here against the best defense.
It routinely happens when a defender leads a heart or a club, but double dummy defenders know to lead spades when in. So, where are the 12 tricks if defenders lead spades whenever they are in?
I see no squeeze that forces East to guard hearts and clubs; even leading the jack of hearts from the South hand doesn't transfer a menace; the eight of hearts is still a guard after West covers.
What am I missing? Inquiring minds (who are still under the impression that I'm smart enough to teach 'em) want to know. (Serves me right for including hand records with double-dummy makes...)

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