Sometimes iBooks won't play an audio book from the bottom up display.
I play audio books with iBooks from my iPad Air running iOS PQ in my car via Bluetooth.
At times, I am unable to play the audio books without restarting iBooks. What I have been trying to do is swipe from the bottom up to bring the display that in iOS 10 now contains an option to play music or iBooks. But when I select play it just sits there forever. I have to unlock the device and close iBooks and restart it to get it to work.
The only I noticed is that if I don't use the iPad then play in the car it seems to work more often.