Coupon not updating order total in Edit Order

I am using Opencart 2.0.3.1

When I go to edit an order in the backend (we had to add a coupon to an already existing order) and add the coupon, it does not update the roder total in the database when I hit "save". However, the coupon is registered in the order totals.

Any idea where this needs to be fixed? I went to the function edit() in the controller, but all it listed were the APIs.

Thanks.

Pictures below.

It registers the coupon in the Edit Order page: After hitting save, the coupon does not affect the order total: The coupon is in the database, but the order does not reflect the correct price: