I had a similar incident on a £1k pair of Fox 40’s and the buyer raised an ebay and paypal claim against me for non delivery!
Even though I provide full tracking info on 48hr delivery, he told me he was out on the day of delivery and also informed me that the postman would not be able to access the property, even to leave a delivery card. My scam warning bell went off at this point.
Thankfully his claim was rejected as I had posted it to correct address given by buyer and Parcelforce provided proof of receipt at the correct address. It may have been signed for by someone else and nicked, it may be a scam by buyer, but I think you should be ok wrt ebay claim.
After that was rejected he somehow managed to raise a claim from Parcelforce for the purchase sum. I raised a query with Parcelforce about this as apparently only the seller should be able to do this?
I’ve provided all info required by Parcelforce, but heard nothing back yet and buyer/scammer has gone quiet. If anything does appear from Parcelforce, I think I’ll just wait to see if buyer contacts me again 😉