Cannot browse App documents after upgrading to iOS 8.3
According to Macrumors:

"Apple has changed security settings in iOS 8.3 that prevent file managers and transfer utilities such as iFunBox, iTools, iExplorer, iBackupBot and PhoneView from gaining access to app directories on an iPhone, iPad or iPod touch. 

The change breaks current versions of transfer utilities for OS X and Windows, forcing many developers to release new versions of their software with workarounds that restore at least partial sandbox access."