Looking for any suggestions or insights anyone can offer...I used USPS LIve Shipping Rates with my Foxycart. Almost since its inception, I get a few customers each month who report the cart does not return a shipping rate (and thus the sale is thwarted). I have looked at this from every possible angle and have never been able to solve it. Some of the things testing has turned up:
1. This is not a matter of the connection to USPS being down (which I know happens sometime). In the cases I'm encountering, it seems more an issue related to the customer. I've been on the phone with them and at the same moment they are unable to get a shipping rate I can enter their identical purchase and address info and get a rate back.
2. The Live Shipping Methods I have selected in Foxycart Admin are correct and not part of the problem
3. At least one of these customers has tried to order multiple times over the course of several years and can never get a shipping rate. I have to take his info over the phone and enter it myself, after which it goes in fine.
4. The vast majority of my customers have no issue.
Any ideas? A setting on the client's browser? A protocol issue somewhere between their IPS and USPS? (This latter would surprise me...I'd expect the only communication needed is between Foxycart and USPS). I'm at a loss.