I had the same issue. By looking in the Chart of Accounts, I realized that the "Contractors" expense type is "Payroll expense". Presumably that's why it's not included in the Projects Overview calculation. So I created a new account on the Chart of Account, as an expense, category "Cost of labor", and called it "Independent contractor". On the Expenses tab I Changed all the expenses from "Contractor" to "Independent Contractor" and bingo that shows up on the Project overview tab