title_body: Non collection books doesn't appear
upvoted_answer: I solved it!
  
  The reason why I didn't see at first place was that my collections were only on the cloud.On the tabs (ALL|DOWNLOADED   and 2 filters on the right corner), I was choosing "collections" instead of "all items" in the first tiny arrow. And the second tiny filter arrow didn't allow me to choose collections (but only recent/title/author). The "collection" selection was faded.
  
  After I downloaded my collections, then choose "all items" on the first filter arrow, "collection" on the second filter arrow, I am able to see my collections as well as my non-sorted books. 
  
  I hope it helps for someone else :)