After a eCommerce order or a Customer order is placed in POS, when you go to Retail and Commerce > Inquiries and Reposts > Store sales, populate a date range and mark all transactions, the Category has no data.

Cash and Carry transactions for the same item does have a Category populated. This is true even when you added the item to the cart by navigating to the navigation hierarchy and add the item.

Because the Category is not populated, you cannot filter the report on Category.