...
When using a barcode sequence, the system verifies the current sequence during each item creation to maintain barcode uniqueness. Consequently, barcodes may not appear sequential if other items are simultaneously created using the same sequence within the institution.
...
Watch Step-by-step instructions are available on the Ex Libris Item Templates video (3:23 mins).
See Working with Items Read detailed instructions available on the Ex Libris Knowledge Center for details, Working with Items.