CStore Essentials unable to support each and every 13 digit UPC Barcodes,
Since 13 digit UPC Barcodes are not considered as recognized barcode, there are some limitations
Only UPC-A and UPC-E Format barcodes have traditionally been used and most recognized barcodes in the United States
This is the reason, with CStore Essentials Price Book, while sending 13 digit barcode Items to POS-Register, some may work and some may not.
Same thing goes with CStore Essentials Item Sales Report, few 13 digit barcode Items may show up under Item Sales Report and other may not generate under Items Sales Report or reflect on Item Inventory.
CStore Essentials allows to Add and Send All 13 digit UPC Barcodes Items to POS-Register. But while doing so, if unable to Scan some of these Items on POS-Register, then you may need to try entering them directly on POS-Register.
Please look into our Help Center article below, for your reference