Tax code removed from Revise SO, but after shipment confirmation tax-exempt status returns in OM SO.

Summary:

Customer has a Sales Order where the Tax Classification Code is initially set to Exempt. When the order is revised to remove the Tax Classification Code (since the customer is no longer tax-exempt), the update is saved and the order is submitted successfully. However, after the order is shipped and shipment confirmation is completed, the Tax Exempt status automatically reappears on the Sales Order. The expectation is that the Tax Classification Code should remain removed after revision and shipment processing. The issue appears to occur specifically during or after shipment confirmation, which seems to reapply the Tax Exempt status on