iTunes doesn't remember audiobook position

I have an aoudiobook that consists of more than 500 individual audio files. Although I do have the option "Remember position" enabled, iTunes, when restarted, never remembers position of the audiobook and always starts playing from the beginning. It does though remember position of each individual audio file, but that doesn't help a lot, since I still have to find the right part I was listening the last time.

It looks to me that "remember position" feature only remembers the position inside one audiofile, but not of the whole audiobook, which is a big drawback