Scenario
Customer added a free shipping item on the Sales Order line however, on the Summary Box, shipping cost is still being charged.
Solution
1. On the Shipping tab of the Sales Order, take note of the Shipping Method.
2. Go to Lists > Accounting > Shipping Items > Edit the Shipping Method set on the Sales Order > Shipping tab.
3. On the Free Shipping Items tab, review if the free shipping item is on the list. Add if it is not.
4. Click Save.