Mass Receipts populating Lot Number with Job Number

When we go to do a mass receipt and click on the line at the top half of the screen to bring the line to the bottom half, the “Lot Number” is being populated by the Job Number instead. We thought that there might have been a BPM somewhere that was doing this, but in tracing this process I only see the following business objects called:
Receipt.ValidateMRPONum
Receipt.CreateMassReceipts
Receipt.OnChangeDtlPOSelected

Unfortunately I can’t narrow it down more than this, because the Mass Receipts window is (needlessly, imo) modal, preventing me from starting the trace right before I select the line and stopping it right after.

In any case, we do not have any method directives on any of the above three business objects.

I also turned on developer mode before opening Receipt Entry, and there are no customizations on either that screen or the Mass Receipts dialog.

I seems like it would be nice for testing to have a way to create a temporary “vanilla environment” in which everything is stock with no customizations, BPMs, or other modifications but still having our database so I could try to confirm with 100% certainty that it’s not something we did or conversely to identify that it is.

Is there somewhere else I could look that might be doing this? Is there some kind of configuration that might cause this?

I know this is an older post but I am currently looking into what in Epicor drives the Lot number to be populated with Job Number during Mass Receipts. I have tested the “Use Job Number as Lot Default” on the Company Configuration and having this unchecked didn’t matter…Job Number was still populated in the Lot. This seems to only occur on PO Release lines where the “Buy For” is Subcontract Operation.

Does anyone know if there is another setup I am missing or is there something embedded in Epicor subcontract logic that is pulling in the Job as the Lot?