I sold an three items to the same buyer and try to combine the invoice. It would not add the discounted shipping into the total. Say each item was $1 and shipping on the 1st was a $1 the next 2 items were .50 each. So the item totals would be $3 and shipping $2.
The combined invoice would show a total of $3 with USPS first class $2.00 off to the side and not in the total.
I know this was long and complicated, but any help would be appreciated. I have done this many times before without issue.