title_body: Kindle Voyage does not show book transferred under Calibre
upvoted_answer: One of the reasons this can happen is if the Calibre "convert to MOBI" preferences form has the Personal Dog tag set to [PDOC]. Then it will not show up in some versions of Kindle in the list of "Books", but it will still appear under "Documents".
  
  Is not possible to change this tag using Calibre. A workaround is to convert it back to EPUB and then again to MOBI, this time making sure that the Personal Dog tag is set to [EBOK] or not set at all.
  
  This thread has a nice discussion of the issue.