Currently if you receive an invoice for something that is a cost that needs to be attached to a job but that item is not on the job you cannot attach the invoice to the job.
We do this a lot with freight,. It order to attach the cost from the AP enter screens you must first add the line to the job, receive the line and then you can attach the invoice. It is super cumbersome. Because it is so difficult it encourages people to not attach those misc. expenses that can be part of a job that are unforeseen.