Hello,
The behavior you describe is logical and there is no kind of bug.
When you see an automatic shipping selection ; there is not. If you do not have a shipping method, the first available one will be selected. That's it !
But if you change your address and the selected shipping method is still available ; there is no reason for HikaShop to change that shipping method (the customer could have selected that shipping method himself !!). So as long the method is available, the method stay selected (obviously) ; only when the shipping method is not more available, that there is no more shipping selected for the cart, only in that case HikaShop will selected automatically a new one.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.