Out of curiosity, did you download the free Episode I around or after September 29, 2009? If I recall correctly, they had first botched it so that if you downloaded Episode 1 for free, it actually downloaded the full game at 6.6GB instead of just episode 1, which was under 2GB. I can't recall how soon they corrected that. I know I received the full game to my 360 and it shows up in my Purchase History. However, I do not have access to Fable II on my Xbox One.
http://majornelson.com/2009/09/29/fable-ii-episodes-debut-today-on-xbox-live/
Off topic, I'll always wonder why they didn't try the episodic approach with Alan Wake, a game literally split into episodes.