Merge pull request #15353 from woocommerce/fix/15245

Set all legacy data

includes/class-wc-checkout.php

@@ -576,9 +576,6 @@ class WC_Checkout {
 				}
 
 				$data[ $key ] = apply_filters( 'woocommerce_process_checkout_' . $type . '_field', apply_filters( 'woocommerce_process_checkout_field_' . $key, $value ) );
-
-				// BW compatibility.
-				$this->legacy_posted_data[ $key ] = $data[ $key ];
 			}
 		}
 
@@ -588,6 +585,9 @@ class WC_Checkout {
 			}
 		}
 
+		// BW compatibility.
+		$this->legacy_posted_data = $data;
+
 		return $data;
 	}