On my iPad 'cloud' I have about 40 books, but when I look at the 'device' part there is only five, no matter how many times I try and sync them.
Obviously I am doing something wrong, but what?
When your kindle is on cloud (black screen with cloud/device at the bottom of the screen) tap the book you want and it will download. It will then Also appear under device.
Assuming that Kindle on iPad is not too different from the Android version, you tap and hold a book in the cloud to mark it, at which point the download option will appear. Synching doesn't download books, it just ensures that the list is up to date
When your kindle is on cloud (black screen with cloud/device at the bottom of the screen) tap the book you want and it will download. It will then Also appear under device.