Yes, looked at that. I have two large games installed there of 50-55 GB each, namely Forza Horizon 3 and Gears of War Ultimate Edition. Total size of the folder is 128 GB, including other Windows Store apps and smaller games. The majority of the space is taken by Steam games (350 GB) and Origin/Uplay (130 GB) with the rest being the Windows and Program Files folders. Most of my user folders (Pictures/Videos/Documents etc) are located on I: so only the AppData folder is on C. I'm sure it's that Unknown allocation of 84 GB and I bet that's Windows using that. As I said earlier it will be released at some point and I'll see 85+ GB free again. Just wish I knew what it was that was using the space. Maybe it's time to change the default install location of Microsoft Store games to one of my hard drives...?