diff --git a/includes/rest-api/Controllers/Version2/class-wc-rest-orders-v2-controller.php b/includes/rest-api/Controllers/Version2/class-wc-rest-orders-v2-controller.php
index 6411a920afa..01a67019e4f 100644
--- a/includes/rest-api/Controllers/Version2/class-wc-rest-orders-v2-controller.php
+++ b/includes/rest-api/Controllers/Version2/class-wc-rest-orders-v2-controller.php
@@ -212,19 +212,19 @@ class WC_REST_Orders_V2_Controller extends WC_REST_CRUD_Controller {
 	 * Merge the `$formatted_meta_data` `display_key` and `display_value` attribute values into the corresponding
 	 * {@link WC_Meta_Data}. Returns the merged array.
 	 *
-	 * @param WC_Meta_Data $meta_item An object from {@link WC_Order_Item::get_meta_data()}.
-	 * @param Object[]     $formatted_meta_data An object result from {@link WC_Order_Item::get_formatted_meta_data}.
+	 * @param WC_Meta_Data $meta_item           An object from {@link WC_Order_Item::get_meta_data()}.
+	 * @param array        $formatted_meta_data An object result from {@link WC_Order_Item::get_formatted_meta_data}.
 	 * The keys are the IDs of {@link WC_Meta_Data}.
 	 *
 	 * @return array
 	 */
 	private function merge_meta_item_with_formatted_meta_display_attributes( $meta_item, $formatted_meta_data ) {
 		$result = array(
-			'id' => $meta_item->id,
-			'key' => $meta_item->key,
-			'value' => $meta_item->value,
-			'display_key' => null,
-			'display_value' => null,
+			'id'            => $meta_item->id,
+			'key'           => $meta_item->key,
+			'value'         => $meta_item->value,
+			'display_key'   => $meta_item->key,   // Default to original key, in case a formatted key is not available.
+			'display_value' => $meta_item->value, // Default to original value, in case a formatted value is not available.
 		);
 
 		if ( array_key_exists( $meta_item->id, $formatted_meta_data ) ) {
diff --git a/tests/legacy/unit-tests/rest-api/Tests/Version3/orders.php b/tests/legacy/unit-tests/rest-api/Tests/Version3/orders.php
index ce6fee73f38..e6ec0cafb1d 100644
--- a/tests/legacy/unit-tests/rest-api/Tests/Version3/orders.php
+++ b/tests/legacy/unit-tests/rest-api/Tests/Version3/orders.php
@@ -337,6 +337,8 @@ class WC_Tests_API_Orders extends WC_REST_Unit_Test_Case {
 			$this->assertEquals( $expected_meta_item->id, $actual_shipping_line_meta_data[ $index ]['id'] );
 			$this->assertEquals( $expected_meta_item->key, $actual_shipping_line_meta_data[ $index ]['key'] );
 			$this->assertEquals( $expected_meta_item->value, $actual_shipping_line_meta_data[ $index ]['value'] );
+			$this->assertEquals( $expected_meta_item->key, $actual_shipping_line_meta_data[ $index ]['display_key'] );
+			$this->assertEquals( $expected_meta_item->value, $actual_shipping_line_meta_data[ $index ]['display_value'] );
 		}
 	}