While it does sound unfair, eBay policy requires you to upload a tracking number by policy. If there is no tracking number eBay will treat it as having never been shipped. This is laid out in their policy pages. You can only satisfy the shipping requirement by using a tracked service and the one indicated by the buyer.

It’s a strict logical operation. eBay sides with the buyer unless all of the following are satisfied:

• A tracking number is uploaded within the specified turnaround time on your listing (I believe it defaults to 2 or 3 working days)
• The tracking number corresponds with the buyer’s indicated shipping service (ex. using USPS Ground Advantage when the buyer indicated Priority Mail will fail this requirement)
• The package was shipped to the exact address given to you by eBay
• The tracking status indicates “delivered” or "available for pickup"
• If the order total exceeds $750, you required a signature for the package

If you fail any of the requirements, you are at the buyer’s mercy. It’s harsh but it’s fair.