There is a rather nasty bug in Metal Gear Solid 5: The Phantom Pain which is causing issues rendering the game’s save files completely useless. The bug is relevant to all platforms, and occurs quite far into the game’s progress.
Konami is working on a patch for the game to correct the bug, but advised that players should not take Quiet as an companion in mission 29 or mission 42 as this will trigger the bug.
Metal Gear Solid V: The Phantom Pain was released last week with positive reviews from both critics and players.