This wasn't a case of a merchant rejecting a card, and for clarification this was with the American Express card, which was a converted SPG card. I posted right before I called it a night, so perhaps my wording wasn't as clear as it could have been.

The payment terminal had the Apple Pay and Google Pay logos on the screen as well as the Tap/Insert/Swipe messaging. I tapped the card, but for some reason the system didn't register the preauth payment, so the receptionist had me present the card a second time. I didn't tap the second time, but I saw that two preauths showed up on my account online. Therefore, it looks like the first preauth with the contactless transaction was in fact successful. I don't know why it didn't register on the receptionist's side.

I remember tmiw trying some contactless payments at Marriott properties in the San Diego area, but I think that was at some of the concessions, not to check in at the hotel. This is the first time I've seen the tap wording and Pay logos on the screen at a Marriott, so I thought I'd try.