AP Invoice (Expense) does not show up in the Project Expenditure

We paid a stipend and it was coded AP to the Project but expense didn't show up in the project expenditure. We think it was because the exchange rate was not setup for the specific time and that's  why not picked up and transferred from AP to Projects. - Is our assumption correct?

Also , is there a way to run a report or know if there are any others, or if this occurs in the future to know there are errors.

Thanks You