If some EAN-13 codes cannot be scanned, it could be that you need to enable UPC-A as they are UPC-A/UPC-12 barcodes.
UPC-A codes are a subset EAN-13 codes in which the first digit of the 13-digit EAN-13 number is assumed to be zero.
The barcode scanner SDK API allows you to enable scanning of EAN-13 (without the subset of UPC-A) and UPC-A codes separately. We recommend to enable both of the symbologies if you are scanning EAN-13, or UPC-A codes.
Since 5.1, although only EAN-13 symbology is enabled, UPC-A codes are scanned too. The codes are returned as a 13 digit EAN-13 code.