Should TaxCloud be passing State Code or State name to TaxCloud for verification?

The site is charging Tax in CA and MA. We are using the latest version of TaxCloud for Zen Cart 1.5.1.

Should a state code or state name be passed to TaxCloud?

When a correct address is passed for Temp Arizona 85287, TaxCloud returns an error.
When a correct address is passed for Tucson Arizona 85730, TaxCloud there's no error. In both cases no tax should be charged.

I logged the values being passed to TaxCloud and the state name Arizona is being passed in both cases.

I contacted TaxCloud and they told me it's because I'm passing the state and not the state code. If that's the case why would it work for some Arizona zip codes. Both addresses validate manually on the TaxCloud site?

My Zen Cart configuration is set to State - always display as a pulldown = true.

The state code in the customer and order records are correct.

Should I be passing a state code. If so, any thought on how the state name is being passed instead or how I should fix this issue?

Thank you for your time and help.