Am having trouble booking a one-way ticket NRT->ICN->LAX for November. Am in the USA and trying to buy with an Amex. The fare is quoted in JPY

I get to the Pay button and click it and then I OK three popops before it actually tries to submit the payment. It just hangs forever:Currently being processed.
Do not refresh.
Please wait.

I have tried this after logging in to my Asiana Club account. It uses passenger name: Lastname FirstnameMiddlename
For name on credit card I tried Firstname Lastname liike on the card. and FirstnameMiddlename Lastname

I tried going in as a guest and got the same issue. At least that showed my passenger name with a space between first name and middle name.

What's the deal? My amex is not the problem.

I tried calling but the message just said "too busy, go away"

ETA: Bought it from Amex. Price was in USD with 24-hr cancel for no fee and able to select a seat on the long haul. IDK why asiana would not sell it to me. The currency options there were JPY or KRW and it did say that if I chose KRW that I would have to use a Korean card to pay. I even tried choosing Japan as the region. Am really looking forward to this (outbound on OZ on a UA award) given my previous experience on OZ for which I wrote a TR.