Shipping address on checkout is not always the default address

Shopify Partner
2 0 1

I have an issue that I change the default address just before clicking 'Checkout' and I have confirmation that the desired address has been set to default, but on checkout I'm not always getting this address to be the shipping address. Sometime it works but sometimes it just stick to an address that previously has been a default address.

Is there any specific Cache, cookies or local storage that is responsible for that? 

Website:, store front password: smartpenguin2015