How does door altar bandos actually work to have him not attack?

I get how red X works please avoid that. how exactly does this method make him not attack though? Theres been a few times i mess up and he seems like he should be in cycle, but he ends up being able to attack me. whats the difference between being in cycle and he cant attack, and him being in the same position and can attack? would love this in a fairly in depth description.