I want to be able to sync PDF files added to iBook across all my 3 devices (MacBook, iPad and iPhone). All iOS devices running iOS 9.3.3 I have followed all the instruction to enable Cloud syncing in iBook: iOS devices: Settings -> iCloud -> iCloud Drive —> Enabled I can put files into iCloud folder in OSX and it will show up in my other iOS device iOS devices: Settings -> iCloud -> iCloud Drive -> iBooks -> Enabled OSX: System Preferences -> iCloud -> iCloud Drive -> Enabled All books purchased from iTunes (not PDF files) are synced across all 3 devices. However, PDFs files are NOT. I have tried adding PDF in OSX and they don't show up in iOS devices. I tried adding PDF files in iPhone, and they don't show up in the iPad or OSX. Did Apple removed this capability? How did you get yours to work?