Manual Order: order number not available in new order emails

As a temporary solution, I did this:

class SequentialOrderNumbersMods {
	
	/**
	 * Class constructor
	 */
	public function __construct()
	{
		add_action( 'woocommerce_process_shop_order_meta',
			[ $this, 'processShopOrderMeta' ], 9, 2 );
	}
	
	// -----------------------------------------------------------------------

	/**
	 * Apply the order number as soon as possible
	 */
	public function processShopOrderMeta( $postId, $post )
	{
		$order = wc_get_order( $postId );

		try{
			if( $postId == $order->get_order_number() )
			{
				$seqNum = \WC_Seq_Order_Number::instance();
				$seqNum->set_sequential_order_number( $postId, $order );
			}
		}
		catch( \Exception $e ){}
	}
	
	// -----------------------------------------------------------------------
}

It’s probably worth noting that you call this action, but only when HPOS is not enabled, currently on line 173. I don’t have HPOS enabled.