There is no guarantee that Kindleunpack will create an ADE-compliant epub from an AZW3. Especially if the AZW3 book wasn't created from an ADE-compliant epub in the first place (or if it was even created from an epub
at all).
Standard advice is to open the epub that results from using Kindleunpack with an epub editor (calibre-edit or Sigil) and edit it to make it compliant with ADE's needs.
Some AZW3's are quite full of ... well ... crap. And KindleUnpack will happily bundle up its extracted contents into a crappy epub.
Good luck!