We had a customer that was unable to complete their order. After updating the shipping information, the "Updating Shipping Options..." bar never responded. When our CSR rep tried it on the CSR's computer, she experienced the same problem. Approximately an hour later, the CSR was able to get it to work correctly.
Since the issue occurred for remotely for a client as well as the CSR, I assume the error has to do with the call to api_json.php not responding at all or at least with "Error" or "OK". If so, any thoughts regarding error catching with something like a timeout or retry for data that doesn't comeback with a valid response?
Let me know your thoughts or if you've heard of anyone else experiencing this issue.