Thanks for the quick reaction!
In this particular case we have an order from €1040 with a transport cost of €30. We refunded the €30 true the refund in the back-end. In the invoice we can clearly see that the price was correct but then at the total we receive €1070 + VAT which is 0 here – Shipping = €1040. The final total should stay the normal price of €1070.
