PRC Distribute Expense Report Costs if change from billabl to non-billable

When an expenditure items is changed from billable to non-billable do you need to recaclucate cost before running PRC: Distribute Expense Report Costs for the accounting change to be properly picked up?  The Project Costing documentation specifically calls out that you need to recalculate costs when you change from billable to non-billable (or vice versa) but I also found documentation that says PRC Distribute Expernse Reports Costs does this.    It seems to work 90+ % of the time to just run the PRC Distribute Expense Report costs but there are a few instances where we have to specifically go in