Originally Posted by czhang

Thanks everyone for the replies. Interestingly, the confirmation number also does not work on the Seibu Prince website. I did use the chat feature from Amex Travel to message the hotel; they noted that they had linked my Bonvoy number and said that I am eligible for Marriott points...I replied back to confirm whether the stay would also be eligible for Ambassador benefits but hopefully that's a good sign...that said, even after they linked my number, the booking will not show up on either Marriott or Prince sites.

Not sure how much to trust the reply from the hotel - or who/what actually determines the eligibility of the stay. Will see what they come back with, but also debating an alternative booking at the Prince Gallery via Chase's The Edit, which provides a similar statement credit and as a bonus is also bookable as a 2cpp redemption... (And is more explicit about supposedly counting for Bonvoy benefits/credit)