Zonos / Australia Post - Shopify charging Commercial instead of Postal

We are setting up our new store to ship to USA from Australia. Our products are made in china.

I have set up Zonos account as per Australia Post’s email. And linked with our Australia Post account.

I have added Australia Post to Shopify, linked account

All HSC codes and country of origin have been entered

I have turned on collect duties for USA

And it works, EXCEPT, when I check on my Zonos account, it is charging us the COMMERCIAL RATE which is significantly higher than the POSTAL RATE.

And from what I have read, we should be charged the postal rate. I have found articles that tell me to go and change my rate to postal in Zonos, but there is no such area! I have reached out to Zonos support Shopify support, Australia Post support, and no luck, I keep going around in circles.

We are selling silver jewellery.

Please help!

I should clarify that the commercial rate is being shown to the customer in Shopify when I am testing the store. eg: on a USD $198 item, it is calculating USD $86.72 in duties. According to Zonos, it should be USD $59.40 postal rate.