I had the similar issue once. After contacting the chat helpline, they told me that one of the BD I selected was from a Seller, hence I was not getting
Amazon GlobalFreeSaver option.
In this case, Seller items are not considered for Free Shipping by Amazon. Only, items sold by Amazon directly are eligible for Free Shipping.
Make sure, you have selected all the items in your cart sold by Amazon LLC exclusively to avail Free Shipping for more than $125 order.
Absolutely right, I did this & did indeed get the free shipping option. Of course they charge customs upfront, but the free shipping compensates 60% of that.. so the end result is still much lower than the local price. Hopefully its delivered with no additional charge!