Can not checkout with apple account balance

Hi. I'm trying to check out with my Apple Account Balance which can cover my whole purchase (an iPad).

However the last step of the checkout process doesn't work. After I choose to use my account balance to pay on the payment selection step and click "Continue to Review", the button grays out for a few seconds, a spinner appears, after a few seconds the spinner goes away, the button becomes clickable again, but nothing else happens. It does not bring me to the review page and there is no error message at all.

Repeatedly clicking the button doesn't help. Using less amount from my account balance and covering the rest with a credit card doesn't help either. Please advise, thank you.