PO Release not closing after multiple drop shipments

We have encountered a situation where the PO release is not being closed when the total quantity has been received. In this situation, the total quantity received was made up of multiple drop shipments. In spot checking a few, it appears that the last drop shipment IS marked Complete. In Company Configuration | Modules | Purchase, Close Release At is set to Arrival.

Could it be that drop shipments are received, but never “arrive”?

Will send this to Epicor as well (and report back) but was curious to know if anyone else had seen this situation and the most efficient way to address it.

I would prefer not to create a BPM to replicate something Epicor should be doing on its own…

Thanks.