Due to the nature of Excel, leading 0s on Product Identifiers, like UPCs, may disappear once the file is saved. Adding the 0s and saving the file, then uploading to Gateway without opening the file again can solve this issue.
1. Open the bulk file and navigate to the Product Identifier column.
2. Insert a new column to the left of the Product Identifier column and title the new column "Product Identifier" also.
3. In the second row of the column, enter the formula "=CONCATENATE("0",[cell name]), where [cell name] is the cell letter and number, and press enter.
4. Continue this formula for all rows that have Product Identifiers without their leading 0s.
5. Once all formulas have been entered, highlight the new column and copy. Click into the first cell of the column, right click, and choose Paste Special > Values.
6. Delete the original Product Identifier column.
You now have a proper Product Identifier column with leading 0s attached. Once all desired changes have been made, save your file and upload using the Bulk Tool without opening the file again before uploading.