In September '22 I had an expensive package go missing/destroyed by UPS. Suffice it to say the claims process is neither straightforward or easy to navigate, so to save other people some time, here is how I finally got to a point of resolution and a check mailed out:

-First step is creating a UPS account on their website and going to https://www.ups.com/claims?loc=en_US . You will file your claim here using ebay's account number, not your own- their UPS account number is 1V534 .

-Next, you will file a claim and UPS will do a search and investigation on your lost package. After this, you will receive an email instructing you to move forward with the claim and upload documents.

-After receiving the email, make sure the claim is filed and you have entered your address, package value etc (complete the claim on their site), but do not bother uploading or trying to upload documentation: Neither will work, because their web system will not recognize the documents as being associated with the shipper's account. Make sure the claim is in progress by going to your claims dashboard in step 1 clicking "check the status of your claim". At this point, you have two options: UPS has a claims department with a separate phone number: 1-800-430-2055 and a claims email: claimsstatus@ups.com . Their retail phone number will not connect you or do anything useful.

-Although you could probably get away with just sending the email with the documentation, I suggest calling the claims center after the claim is filed and you've received confirmation, and let them know you want to send an email with the relevant info they need. You will be providing a screenshot of the transaction in your ebay seller dashboard that shows the order and the tracking number, and order total. You'll also be providing a completed claim form that should've been provided to you after filing the claim originally- it's a 2-page PDF that I used an online tool to modify/write on. Put your tracking and claim numbers in the subject line of the email along with ebay's account number.

-after this, if you still have not heard anything or received a check after about a month, you'll want to call claims support again at the number above and give them your info, then ask to speak with Centralized Exception Resolutions. They will connect you and that team will help expedite your claim and fill in any missing info / solve any additional weirdness.

That's about all you have to do (lol). It will take up to 2-3 months to complete all of this, although with the knowledge here it could be done in weeks or less. Note that I may have missed something, I tried to include all info that I could remember about the process but as you can see, it is highly complex and very hard to streamline. Mostly this is because you are not using your own account to ship an item. Note that if you do this wrong, ebay will be sent the check- to avoid this, try to follow these steps as best you can. Mod info- all of the emails and numbers, etc. above are public knowledge and there is nothing in this post that could be used maliciously, so there is no need to worry from that end- most of this info is just hard to find. I hope this post gives people some hope that you can successfully file a claim with UPS if you ever have to.