eBay's notification showing Delivered, is notoriously slow to update.
As long as you have tracking to show delivery, this is all that is needed should a buyer open a case for item not received.
Personally, I never look to see if an item has been delivered, because I'd be the first to know, from the buyer, if it wasn't, and that is the time then, to check that tracking against Royal Mail's Track & Trace or whichever courier/postal service was used.
@wark40
