title_body: collection shows as empty and refuses to populate -- not syncing properly
upvoted_answer: I think I see the problem (or one problem at least). 
  
  I have a massive set of collections on the kindle app for android. (Like 50 collections holding 2000 or more ebooks). 
  
  But when I install the Kindle for PC app for my Windows desktop, it does not let me import the organized collections from the Kindle app for android. When I use the Kindle for PC app, there is an IMPORT COLLECTIONS option, but it prompts me to choose between two older devices instead of my current android devices. These older devices used a type of collections which is different from the current one. 
  
  If I create a NEW collection on Kindle for PC and add ebooks to it, this new collection does not appear on my android app or even on Manage Your Content and Devices page. 
  
  You would assume that collections propagate to all Kindle platforms, but what I'm seeing now is that any collections you create on Kindle for PC will not be propagated onto your other reading systems. As you see, you can still access your ebooks, but you can't use the collections from your other devices. 
  
  You're not doing it wrong; the Windows program is just using an incompatible kind of collection system. 
  
  On the plus side, any collections you make on Kindle for PC are just for that computer -- and nothing else. (Just to be safe, I would create only a small number of collections on Kindle for PC). I have verified that annotations on the Kindle for PC propagate (albeit slowly) to other devices.