iOS 11 how to prevent iBooks from moving my books to the cloud? I see that my iBooks seems to be uploading my books to the cloud without keeping a copy on my local device. So when I reopen the app, I have to wait for the book to do finish downloading (which is a hassle if it is a 600 page pdf)

How can I prevent iBooks from deleting local book files and moving them to the cloud?

Is this related to “offload I used apps” switch? (it’s on for me)
This is a bug in iBooks.  Please report it to Apple so they fix it.  Many of us have this problem.  I just got bit by it on an airplane flight, when I realized I didn't have my books on my iPad or phone because... Apple.