I know many chippers prefer to use less expensive shipping methods that do not include tracking, or they purchase postage with tracking but they buy it at the postal counter and don't enter the tracking number into the Ebay sales record. Ebay has a new policy for Ebay sales if you ship that way: if a buyer says they didn't receive merchandise, sellers will not be able to challenge this if they did not upload tracking info early in the process (before the scheduled delivery date has occurred). You will not be able to load a tacking number after a dispute has arisen.

From Ebay:
Starting September 10, 2018, you will be required to upload tracking in the structured data field before the estimated delivery date has passed in order to appeal an "item not received" claim. eBay will not protect you from a claim if you send the tracking number to the buyer via email.

Without tracking information, eBay can't protect you because we won't be able to confirm your item was delivered. Tracking also benefits buyers by enabling them to track the status of their deliveries. We will also update the eBay Money Back Guarantee policy with the new guidelines.

It appears that an automatic refund is going to be Ebay's solution