Anders from the Shopify Social Care team here. Thanks for reaching out today.
That certainly sounds like a bit of an odd error. To confirm, once you've entered all of your shipping information, proceed to the payment selection of the checkout, select AfterPay and then 'Complete Order' - you're redirected back to the previous checkout page? If this is the case, I'm thinking this could be a possible browser or device issue. When I place an order on your shop, I'm able to be redirected to Afterpay to enter in my account information:
I suggest ensuring that your browser is up to date, and if the issue persists, I would next try a different device to see if you narrow down what is causing the issue. I would also use a different shipping address (like a family member or friend) to test out the functionality. Contacting Afterpay support would also be a good option.
Let me know how those troubleshooting steps go!
I got solution. This was happening because My client disabled TEST Mode for Shopify payments But... TEST Mode was enabled in AfterPay.
After disabling TEST Mode of AfterPay, it worked.
Therefore, I believe TEST Mode **should be same for all payment options **- either enabled or disabled.