Am I being ignored after an interview?
Well, I had quite a few postdoc interviews and I can tell you that it is NORMAL for a PI not answer you back. Of course it is a shitty situation, even more when you thought the interview was good, but that's how life is when you are searching for postdoc positions.
1 email as a follow up or an update is ok. But don't insist on it. The truth is: you know as soon as you finish the interview if you would hire the applicant or not, so if you don't hear from them after a week consider it a no.