iBooks synch keeps removing all books
Hi,
I have over 1200 ebooks that I like to store on my iPad. There's been a few times in which I wanted to add just a few more books to my collection, only to have iTunes remove them all during the synch process. I always have to re-synch them all, which takes over and hour. I see that iTunes has a "manual" manage option, but it's just for music and videos, not books. Is there a way that I can set everything so that when I add one book to my iPad, I don't end up having to re-synch my entire library?
iPad Mini, iOS 8.4