Am having same trouble with covers. But in addition, I cannot sync furthest page read properly with Personal Documents. It only works one way. Furthest page read on Fire will sync to Kindle Keyboard, but not from Keyboard to Fire. Bookmarks, however will sync both ways. Amazon tech support says this is by design! Crazy.
For what it's worth, this is the message I sent to Amazon Feedback:
Sync of Personal Documents on Kindle Fire NOT AS ADVERTISED. It won't sync FROM anything but another Kindle Fire.
I can close a book (non Amazon, but emailed and converted through Personal Doc Service) on the Fire, and when I open that same book on my Kindle Keyboard it will sync to the furthest page read on the Fire. But it won't work the other way around. That is, close the book on the Keyboard, and open it on the Fire, it will not sync to the furthest page read from the Keyboard. It says I am already at the furthest location across all my devices. NOT TRUE.
I called customer service, was transferred to tech support, and was told that the 2-way syncing of Personal Documents works ONLY BETWEEN TWO KINDLE FIRES. To me this makes no sense at all. Why would I own 2 Kindle Fires for my own personal use in the first place? And if two of us on the same account owned Fires, we'd probably turn off the syncing feature anyway to avoid confusion in reading the same documents or books.
The deal with the new 6.3 update seemed to indicate that this syncing of Personal Docs worked among all supported devices and apps. That does not seem to be the case.
Strangely it DOES SYNC BOOKMARKS. So if I remember to do it, I can bookmark the last page read on the Keyboard and it WILL show up among the "Notes and Marks" on the Kindle Fire when I open the book. However, my point is that I shouldn't have to do that (and will often forget to). Your info says it should also automatically sync the furthest page read, yet it definitely does not.
Here is what it said on the Amazon website:
"Whispersync for Personal Documents
Whispersync allows you to sync your notes, highlights, bookmarks, AND FURTHEST PAGE READ on your personal documents that have been converted to Kindle format using Kindle Personal Documents Service. Kindle Personal Documents Service also stores your personal documents in your Kindle Library for viewing and downloading to supported Kindle devices and Kindle reading applications. These features are currently supported on Kindle Fire, Kindle Keyboard, Kindle, Kindle Touch, and Kindle for iPad, iPhone, iPod touch with Kindle app version 2.9 or greater.
THIS IS OBVIOUSLY NOT TRUE AS REGARDS THE SYNCING OF FURTHEST PAGE READ AMONG ALL SUPPORTED DEVICES. THE FIRE IS ONLY SUPPORTED "ONE-WAY" among ALL devices, and TWO WAY only among FIRES! This is really not terribly helpful.