I couldn’t find a topic with this exact issue. I recently updated my Master Chief Collection. I hadn’t played it since February. After the update I have lost all my progress. It still asks me if I would like to resume at mission 7 on Halo 3 which is where I left off but it says I haven’t completed any missions and all my accolades are gone. Funny enough it still shows my save file on my hard drive from before. When I go to play offline it says it can’t access my cloud save and would I like to play offline without my savefile. You go to manage game and it clearly shows a savefile for my username. It’s acting like it can’t access my savefile and when I do go online and it accesses the cloud save I have no progress. It appears the cloud save is the same KB as my hard drive save so they may be the same I am not sure. I also always played my Halo MCC online all the time so the cloud save should be the most recent. I would really like to find a resolution for this because if I can’t I need to cancel my Halo 5 preorder before it releases tomorrow.