Originally Posted by kovidgoyal
It might be that the Kindle simply took a little while to index the newly added books.
I think you may have something there... I just moved a single book (converting from EPUB to MOBI) and it showed up fine, although not with a cover. This was a book that I was reading on my Sony T2, so I wanted to go that same place on the Kindle Paperwhite. A search for text kept reporting that nothing was found and that the book was not indexed yet. After several attempts and about 1/2 hour later it finally worked...
So it may be that the Kindle takes awhile for it to update newly added books. On the Sony you can see that a process is occurring after a disconnect from the computer, but there is no such indication on the Kindle.