After you upgrade to Windows 8.1 Preview, you cannot view your library data in the Kindle Windows Store app.
This issue occurs because Internet Explorer looks for the library data by using parameters that are specific to Windows 8. Therefore, Internet Explorer cannot find the stored data in Windows 8.1 Preview.
In most cases, an update (2863638) that includes the same fix is applied at the same time when you install Windows 8.1 Preview.
If update 2863638 is not installed, you may apply update 2863532 through Windows Update before you use the Kindle app for the first time after you install Windows 8.1 Preview.
If you have run the Kindle app any time before installing update 2863532, uninstall and then reinstall the Kindle app after update 2863532 is installed.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.