It has been 10 days, and I have not received the miles. I called ANA and was told AMEX had a transfer error on May 17 and 18, hence the transfers initiated on these two days would not post. I was also advised to call AMEX to reprocess. So I called AMEX. They counted how many business days had passed since my transfer so that they would bother to take a look. Seeing I'm already past biz day 7, the rep called his supervisor, who insisted no issue on Amex side, but they filed a case for further research.

BTW, I did another transfer to ANA on 5/23, and posted on 5/25, so it looks like what ANA told me was true, and the issue is gone.