Draft invoice - line item totals to zero

When we tried to generate a draft invoice for a project where the line item in travel was reversed such that there was a zero net total on that category - the in and out adjustment amounts did not appear on the invoice and the billed flag automatically got set to Y for the transactions.

In another expenditure category - we reversed the line item but also had new transactions - so the new transactions plus the reversals showed up - here is an example to explain clearly

Travel 

Exp item id - 123  - amount $500

Exp item id - 345 - amount  - $ 500