It looks like the trick is to return to home before exiting the app to establish the current location on the Amazon servers. I'm not sure how reliable this will be but it can work. Downloaded the book on both devices and did the same steps noted above and the sync appears to be working. Since I established that the sync can work, I noted down my location in the original book that wouldn't sync and then deleted the book from both devices. When I opened the book on my 920 it asked and advanced to the correct page. I then advanced a few pages then returned the 2520 Kindle App to home and closed it. When I opened the book it asked me if I wanted to go to the furthest location. I then returned the Kindle App to home before closing the app. I downloaded a new book on the 920 and moved forward a few pages. I believe there is at least one wireless solution for connecting your Kindle to your Calibre, but in the end I stuck with using the USB connection, as by the time I need to move some books around, I need a recharge, so i get a two for one deal (load and charge).I was able to get the sync to work. Once a week or so, I sit down at the PC, remove some books from my Kindles, mark them as read on Calibre (tag 'read'), add some new books to the appropriate kindle ('paperwhite' for reading in bed, 'keyboard' for text to speech while commuting) and tag the books I am currently reading in Calibre by the device they are on. My 1263 (current count) works are stored on Calibre, I download from Amazon, Smashword, Baen, Project Gutenberg, etc. I won't go into all it's advantages but, essentially it is your own personal library, that you can organize and store you books on, regardless of where it comes from. The only disadvantage the Calibre has it is a bit more difficult to connect wirelessly to your collection. I searched for solutions and read many articles & blogs, I strongly desired an Amazon/Kindle solution, the majority pointed to a single solution which I eventually adopted. I was trying to keep track organized with an Excel book. I personally have some OCD issues that require my books be in some kind of order that is not primary based on who I bought it from and when. If you have works from anyplace else, then the prospects get worse.

If every book on your devices is from Amazon, then you can do some organizing at 'Your Account' > 'Manage Your Device' > 'Your Kindle Library' or by using the cloud. I am guessing you have already found Amazon's Organizing Your Kindle Content.

When does kindle app sync