Upon adding the tiered-price item to the basket
The unit price that corresponds to the quantity initially added to the cart is what carries forward and is displayed in the mini-cart for the unit price - this is expected.
The total value of the order is calculated correctly per the unit price.
Upon changing the quantity in the mini cart
The unit price shows a progress indicator suggesting it is updating per the quantity change
The unit price REMAINS what was originally reflected when first adding the item to the cart with a particular quantity - irregardless of the new adjusted quantity.
The total cost is calculated CORRECTLY - implying the correct unit price for the adjusted quantity is being used to calculate the total price but is simply not being presented as an updated unit cost per the quantity change