Hello,
I discovered a solution. If your shipping method is calculated based on zip code, you can use this Java Script code to force the update.
Use this code on your checkout page:
<script type="text/javascript">
jQuery(function ($) {
$("body").on("blur", "input#shipping_postcode, input#billing_postcode", function(e) {
var postcode = $(this).val();
if(postcode !== ""){
console.log("The postal code was entered");
//Force checkout update
$('body').trigger('update_checkout');
}
});
});
</script>
If your shipping methods use the state, you can modify the code to identify the state change.