losing US domestic sales due to "shipping not available for the selected address"

Shopify Partner
13 0 3

I'm having a lot of customers get this error message when checking out of late "shipping not available for the selected address". The strange thing is that I can rarely recreate the error, it somehow seems specific to either the users phone or browser/phone combo.


Anyone else having these problems of late, as in the last 4 months or so?


This is killing me as sales are already very slow these days.


FYI I have a third party fulfillment warehouse providing shipping rates, but they can't find a bug on their end.