Scan inbound stock transfers using UPC code instead of SKU#?

Currently, most of the functions in DEAR WMS app supports the scanning of UPC barcode, but only the transfer receiving does not support the scanning of UPC barcode. Only SKU#/Batch#/Serial# are supported for transfer put away, but all of the products only have barcode labeled and not SKU# labeled. SKU# is only printed on the label but not in a form of scannable barcode. I'm wondering why DEAR supports UPC barcode scanning for its WMS app in most of its picking, packing, PO receiving, but only not available in its transfer put away.