My audiobooks are not recognized by my iPhone after upgrading to iOS4. They worked fine prior to upgrade. They sync, but are not seen by the ipod app. When I select audiobooks it displays a white image with "No Audiobooks" on it. I know they are transferred to my iPhone because they show up in iTunes-Devices-iPhone-Books, and eat up a lot of memory. The only way I can get them to play is if I create a playlist and sync it, and select playlists. Anyone else have this problem?
Go to Settings (the settings app)
Then General
Then Restrictions
Then touch Disable Restrictions (if they aren't enabled)
Your audiobooks should reappear.
To be more specific I think it has something to do with the Movie restriction settings but by disableing all the restrictions your audiobooks will reappear for sure...
I also had the problem of my audiobooks from Audible not showing up after the 4.0 upgrade. I took the advice of some previous input and on my iphone(3G) went into Settings on the iphone, then General tab, then Restrictions tab and turned off the restrictions on the iphone. That did the trick! Thanks for the advice. Wish I wouldn't have restored my iphone already. I lost a lot of data and settings in the process.
This also worked for me. I had checked the sync books and never scrolled down to see that there was the sync audiobooks section. Not sure how it is differentiating the two but it is now syncing for me.
I can confirm that the restrictions issue is happening for me as well. I just found this thread after discovering the solution to the bug myself yesterday. I wish I would have found it earlier, it would have saved me several restores 🙂