Hi @bisratlearn,
Thanks for your reply.
I followed your instruction, and now the problem is solved. Here is the main reason of the issue:
In the shipping zone setting, I have ‘Auckland’ and ‘non-Auckland’ two zones to cover all of the areas in New Zealand. Somehow, one of our admins created the 3rd shipping zone which has no shipping options and also covers New Zealand area. So there is conflict happened. When users select an area which is supposed to be ‘Non-Auckland’, the system actually recognise it as a ‘New Zealand’, and under ‘New Zealand’ shipping zone there is no shipping option.
After I deleted the 3rd accidently-added shipping zone, the problem is solved.
Thanks a lot for the help!!!