360GameSaves tells that in the Spring Update, Microsoft has implemented a new protection against gamesaving by using 360GameSaves gamesave archive against them. Microsoft went through 360GameSaves gamesave archive and downloaded all the saves, then everyone who has uploaded saves in the past has had their current local "ConsoleID" values added to a Console Revocation List implemented in the new spring update.
Any gamesave coming from these ConsoleID values is now recognized as corrupt in the latest update. Which means if your on the list, saves created on your console will now only work on your console. Your transfer privledges have been revoked.