With HPOS + compatibility mode enabled, manually created subscriptions don't have a start date in the new order tables

changelog.txt

@@ -4,6 +4,7 @@
 * Fix - When HPOS is enabled, make the orders_by_type_query filter box work in the WooCommerce orders screen.
 * Fix - Resolved an issue that caused paying for failed/pending parent orders that include Product Add-ons to not calculate the correct total.
 * Add - Introduce the "Subscription Relationship" column under the Orders list admin page when HPOS is enabled.
+* Fix - Store the correct subscription start date in postmeta and ordermeta when HPOS and data syncing is being used.
 
 = 6.2.0 - 2023-08-10 =
 * Add - Introduce an updated empty state screen for the WooCommerce > Subscriptions list table.

includes/data-stores/class-wcs-orders-table-subscription-data-store.php

@@ -609,6 +609,11 @@ protected function persist_order_to_db( &$subscription, bool $force_all_fields =
 			];
 
 			if ( empty( $existing_meta_data ) ) {
+				// If we're saving a start date for the first time and it's empty, set it to the created date as a default.
+				if ( '_schedule_start' === $new_meta_data['key'] && empty( $new_meta_data['value'] ) ) {
+					$new_meta_data['value'] = $subscription->get_date( 'date_created' );
+				}
+
 				$this->data_store_meta->add_meta( $subscription, (object) $new_meta_data );
 			} elseif ( $existing_meta_data->meta_value !== $new_meta_data['value'] ) {
 				$new_meta_data['id'] = $existing_meta_data->meta_id;
@@ -649,7 +654,7 @@ protected function init_order_record( \WC_Abstract_Order &$subscription, int $su
 				continue;
 			}
 
-			// If we're setting the start date and it's missing, we set it to the created date.
+			// If we're reading in the start date and it's missing, set it in memory to the created date.
 			if ( 'schedule_start' === $prop_key && empty( $meta_data[ $meta_key ] ) ) {
 				$meta_data[ $meta_key ] = $subscription->get_date( 'date_created' );
 			}

includes/data-stores/class-wcs-subscription-data-store-cpt.php

@@ -221,6 +221,10 @@ protected function update_post_meta( &$subscription ) {
 		foreach ( $this->get_props_to_update( $subscription, $this->subscription_meta_keys_to_props ) as $meta_key => $prop ) {
 			$meta_value = ( 'schedule_' == substr( $prop, 0, 9 ) ) ? $subscription->get_date( $prop ) : $subscription->{"get_$prop"}( 'edit' );
 
+			if ( 'schedule_start' === $prop && ! $meta_value ) {
+				$meta_value = $subscription->get_date( 'date_created' );
+			}
+
 			// Store as a string of the boolean for backward compatibility (yep, it's gross)
 			if ( 'requires_manual_renewal' === $prop ) {
 				$meta_value = $meta_value ? 'true' : 'false';