Those errors happen when a page is missing from the bing search engine cache, you can go to
https://www.bing.com/search?q=Heart+...www.amazon.com and click the green arrow next to the result to get the cached page and see for yourself that the cached page is missing.
You can always try a different source of amazon metadata by configuring the amazon plugin in Preferences->metadata sources to use either google or the amazon servers instead.