Same issue here. Three tickets BKK-SIN and refuses to go through (tried different browsers with Chase UA Visa). Chase said it did not make it to their system. Talking to live chat now.

* Update: used the Live Chat in the browser and this is what it took to get it processed.
1. Fortunately Singapore sent me a booking code/PDF to my email. Not ticketed. Gave that to the chat agent.
2. Chat agent recreates the purchase (three tickets under one booking code) under a new booking code and emails it to me and I have to go to "Manage Booking" tab on the website homepage, put in that booking code and last name. Takes me to online payment page and fails again.
3. Chat agent has to call me on my mobile number. She says I will get routed to a phone payment system which asks for CC#, CV, and exp date which I put in and then routes me back to chat agent on the phone.
4. SUCCESS! I get three separate Singapore emails with e-ticket PDF receipts for myself and my two family members traveling with me.

What trial and tribulation!