Shipping volume calculated by product, not variant

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-- HikaShop version -- : 2.2.1
-- Joomla version -- : 3.2

Let's say:
I have a product, it's volume is 10 cm^3
Variant 1 of the product has a volume of 20 cm^3
All shipping methods are made by using the manual plugin.
I have shipping method 1, whose maximum volume is 15 cm^3
The maximum volume of shipping method 2 is 50 cm^3. Its minimum volume is 16 cm^3

If I have only my product without a variant in the cart, shipping method 1 is selected, what is right.
If I have only Variant 1 in my cart, shipping method 1 is still selected. Why does it not select shipping method 2? I think the selection is based only on the volume of the product - if a variant has a higher volume the shipping method is not selected right.

Thanks in advance.