Does QuickBooks Online Automatic Sales Tax override tax classifications on Refund Receipts created via the API?

We're trying to determine whether the behavior we're seeing is expected with QuickBooks Online Automatic Sales Tax (AST) or whether something in our integration should be handled differently.

Our workflow is:

Shopify → Cin7 Core → QuickBooks Online

Here's what we're seeing:

• Customer purchases through Shopify.
• The sale syncs through Cin7 Core into QuickBooks Online.
• The original Invoice has the expected tax classification.
• Later, the order is refunded.
• The refund syncs to QuickBooks Online as a Refund Receipt.

The refund amount is correct.

The sales tax amount is also correct.

The tax percentage matches the original sale.

However, the Refund Receipt is assigned "Automated based on location" instead of the original tax rule used on the sale.

Because of this, the accounting totals are correct, but the refund is classified under a different tax bucket than the original transaction, which affects our tax reporting and reconciliation.

Cin7 has explained that the tax amounts are correct and suggested this behavior is related to QuickBooks Automatic Sales Tax. We're trying to understand whether this is expected behavior within QuickBooks.

Our questions are:

1. Is it expected that Refund Receipts created through the QuickBooks Online API are classified as "Automated based on location" when Automatic Sales Tax is enabled, even if the originating transaction used a different tax rule?
2. If a third-party application includes the original tax reference (for example, TaxCodeRef, TxnTaxDetail, or another tax-related field) when creating a Refund Receipt, will QuickBooks preserve that tax classification, or will Automatic Sales Tax replace it?
3. If QuickBooks determines the tax classification, is there any supported way for third-party integrations to preserve the original tax rule from the sale on the corresponding Refund Receipt?

We're not trying to determine whether this is a Cin7 issue or a QuickBooks issue. We're simply trying to understand how QuickBooks Online Automatic Sales Tax is designed to behave so we know whether what we're seeing is expected or whether there's an integration issue that should be investigated.

Any guidance from someone familiar with the QuickBooks Online API or Automatic Sales Tax would be greatly appreciated.