Bug: "must be blocked" and menace

[rex4]

I was doing Possibility storm Dominaria #00 puzzle, and it's just impossible to solve it (I checked on the website for the solution) because when you attack with the creature which has "must be blocked" menace and flying, 1 enemy which you gave reach + the one with flying are supposed to be forced to block it, and they simply ignore the rules.

It doesn't only mean that AI can cheat, it also mean that players can cheat too, even versus other players.