= Solution
Here $\langle+y|=(\langle0|-i\langle1|)/\sqrt2$. Keeping that <complex conjugation>, the joint amplitude is
$$
(\langle+|\otimes\langle+y|)|\psi\rangle_{AB}=\frac1{2\sqrt2}\bigl(1+(-i)(-i)\bigr)=0.
$$
Hence \b[$\Pr(A=+,B=+y)=0$]. The cancellation is destructive <quantum interference> between the two source components, not the absence of either local outcome. Each local outcome individually has <probability> $1/2$, since each <reduced density matrix> is $I/2$. Omitting the conjugation in the second bra would turn the cancellation into reinforcement and give the wrong answer.
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