If you have experienced this issue, here is a workaround.
1. Load your Episode 4 save game.
2. Pause the game and exit to the Main Menu
3. Select the save file you'd like to play and continue gameplay from that slot
4. When ready to exit the game, Pause the game and return to the Main menu
5. Select Exit game
If you experience this issue and the one save that loads is not from Episode 4, starting Episode 4 from that save slot and then following the steps above will resolve your issue.
Please note: Always exiting the game from the Main Menu (as opposed to using the home button, for instance) will avoid this issue!