Price doesn't update when amount of product variation gets updated

Problem/Motivation

When you have a price list where a certain product variation gets a different price based on the amount of products that get ordered and you add an order item with a certain amount, save that order item and after that edit that order item and change the amount which would cause the price of the product variation to change, the price doesn't get updated.

In my case, I have a product with a default price of 0.80 and when 5 of these products gets ordered, the price drops to 0.75 per product. When I add an order item with amount = 10, the product price gets correctly set to 0.75, but when I then change the amount to eg. 2, the price remains 0.75, while it should be updated to 0.80.

Steps to reproduce

• Have a price list where a product variation gets a different price when ordering X amount.
• Create a new order where you add an order item with the amount above the previously set threshold.
• Save the order item. (NOT the order)
• See that the price per item gets correctly set to the price when ordering more than X amount.
• Edit the order item and change the amount to a value below the previously set threshold.
• Save the order item again.
• See that the price remains set to the price when ordering more than X amount, instead of being changed to the value when ordering less than X amount.