Im having the same issue when adding products directly from Aliexpress using the chrome extension.
I have set my default shipping method to ePacket in oberlo settings but when I import a product from Aliexpress the shipping method is set as Yanwen Economic Air Mail and I cannot change it.
Attached some images to show what I mean.
When I add products from Oberlo marketplace it is selected as ePacket and shows correct shipping price.
