Running macOS 10.13 beta 5 - attempted an online purchase in Safari using Apple Pay via Fingerprint ID on MacBook Pro c touchbar. Got popup saying "Apple Pay failed to work. Try again" or similar verbiage. The popup disappears too fast to study of copy. So, I tried again - same popup. Tried a third time - same popup. Finally, I gave up and usde a credit card. Unfortunately, I received Confirmation e-mails on ALL FOUR PURCHASES, three of which had the nice little Apple Pay logo on them. Now I will have to deal with the seller.