Microsoft is pushing a new cumulative update for Windows 10 that aims to fix an issue with privacy settings being reset for "an extremely small number of people" after the November update was applied. Here's the description from Microsoft:
"Recently we learned of an issue that could have impacted an extremely small number of people who had already installed Windows 10 and applied the November update (Version 1511). When the November update was installed, a few settings preferences may have inadvertently not been retained for advertising ID, Background apps, SmartScreen Filter, and Sync with devices. This issue has been fixed in the update that accompanies KB3120677."
The issue with retaining privacy settings was also the reason behind the recent disappearance of the November update in Windows Update, as well as the media creation tool. Now that the issue has been fixed, both the update and media creation tool are once again available to download. As for those who had already installed the November update, Microsoft says that it is working to restore previous settings "over the coming days."