Comment 1 for bug 1433125

This is how the amazon.com server works currently. Amazon does not
return Kindle editions of that book in the search results unless you are
logged in. Try it for yourself, log out of amazon (or better use the
private browsing mode) in your browser then search for B004JHY6OG, you
will get no results. Log back in and repeat the search and you will get
the Kindle edition.

Remove the ASIN from the metadata and change the title to "The Heroes"
and you will get results. The title "The Heroes: A First Law Novel" is
only found in the Kindle edition, so it again will not work.

I have no clue why the amazon server is behaving this way, but there is
nothing calibre can do to make up for it's misbehavior. You can try
reporting the misbehavior to amazon, but I wouldn't hold my breath.

 status invalid