When you enable Shopify to track your inventory, make sure you understand how items are counted and tracked when you receive them from the supplier. The number of incoming items will vary based on the items that you’ve received (regardless of whether you mark them as Accepted or Rejected).
You can find the number of incoming items for a product on the product's details page in the Inventory section (or in the Variants section for product variants).
For this example, let's use a transfer with 10 items.
If you've ordered 10 items, received 7 of them, and marked 4 as Accepted and 3 as Rejected, there will be 3 incoming items for that product. This is because you've indicated that although 3 of the items that you received were not in the condition that you expected (the 3 that you marked as Rejected), you still received 7 of the items that you ordered.