Hi JackHo ,
Thanks for your product.
I'm sorry, but that's not a bug. It's the expected behaviour.
A Purchase Order is a record of your purchases. Its lines show the name of the product when you created the Order. If you decide to change the name of the product for any reason in the future, the order will (and should) reflect the historic name (At least, that's how we decided it based on our business logic).
Best Regards,
José Andrés