I downloaded the episode 4 for Xbox last night. Fired it up just a bit ago with my wife watching. I went through the usual, continuing from where I left off. I selected my save from finishing episode 3.
Some animation began, so I was ready for the next episode. I was surprised to see myself in the back of a cop car. My wife asks if I started a new game. No, I didn't.
Well, just to make sure, I paused and used the Main Menu option. Then went back in to load my save once more. But my nice end of episode 3 save is now a brand-spanking-new start of episode 1 save.
So I just lost all of my previous data, from all three episodes, in an attempt to load my old save. Had I known the buggy nature, I would've been paranoid and made a backup. Now I just have to hope I remember every single choice I made in the previous three episodes, and waste a whole bunch of time recreating it.
I really enjoyed the game up until this point, having had few bugs in the previous episodes. Very disappointing.