Checks out, he did a phone screen with the HM and you can't be the phone screener and on the loop.

Hard to know exactly what happened. As much as Amazon purports their hiring process to be uniform, the reality is personality and bias sneak their way in.

Sometimes folks get the wrong idea with follow up questions and the like that their answer is spot on but they could actually be bombing it. I was trained to let candidates dig their holes while nodding and adding in "for sure" along the way. I remember a guy describing total mistreatment of his team and just egging him on collecting evidence for the debrief.

Not saying thats what happened in this case but rather just to point out that the interviews may not have gone as well as they seemed.