Use this if your Amazon wishlist has mysterious items that are unhelpfully "no longer available". While on the offending wish list page, open your browser debugger console and run this to get a list of IDs for the "no longer available" items. Paste them in to Google and there's a very good chance you'll find out what that item was.

gistfile1.js

(function () {
  let result = document.evaluate('//span[contains(text(), "is no longer available")]', document.body);
  let node = null;
  while (node = result.iterateNext()) { console.log(node.id.replace(/^itemName_/, '')) }
})();

I had pretty good luck with the 6 missing items on my wishlist using the ASINs. I had to search without the "ASIN" prefix for a couple of them, and I had to use Bing to find one, but I was able to track down what they all were.

Looks good, though weirdly I am seeing the details on my "discontinued" items on my wishlists now as-is so I can't try it out myself. The links (one example here) are 404s.