This happened to me just after downloading and starting Episode 5. Suddenly I was right back at the start of Episode 1 with a gamesave to match. Felt physically sick. So I came on here and found this advice. I'm now able to get going on Episode 5 but it seems not all my choices have carried over. I ended Episode 4 with the whole group with me (I even took Ben!) but starting Episode 5 I only seem to have Kenny, Christa and Omid now. Pretty disappointed but it seems like the best I'm going to get so I'd better get on with it.
Hold on Clementine, I'm coming for you.