Getting audiobooks from iTunes library on my Mac to the iPhone
I have a number of audiobooks in my iTunes library that I cannot find on my iPhone. A few are in the audiobooks section of Books, but many are not. How can I get them to the phone?
Audiobooks is a separate category of syncing settings in iTunes ( https://support.apple.com/en-us/HT201253). Are you already specifying items to sync in this way?
Additionally, you can drag audiobooks in your library directly to your iPhone in the sidebar.
For me, I found the iTunes syncing cumbersome. I use the app called Bookmobile and find it so much more simpler and efficient to manage audiobooks.