Windows 10 build 21277

Windows 10 build 20270 is the twenty third Insider Preview of Iron. A screenshot was shown by a Microsoft employee on 30 November 2020, and the build itself was released three days later to all Insiders on the Dev Channel.

Changes

 * The "Advanced View" checkbox for the Drive Optimizer, which was added in build 20241.1000 but was nonfunctional, is now working properly.
 * Using the touch keyboard in a portrait posture on a 2-in-1 touch device now supports split keyboard mode. This change was initially added to the Beta Channel as part of the Feature Experience Pack update.
 * The timebomb was extended from 31 January to 31 October 2021.

Bugs

 * Live preview doesn't work for pinned site tabs on some machines.
 * Some users are seeing error 0x80070426 when using their Microsoft account to sign into various apps. Restarting usually fixes this.
 * The modern Disk Management page (Settings → System → Storage → Manage Disks and Volumes) in the Settings app is blank, as a result, it won't display any drives present. To workaround this issue, use the classic Disk Management tool to manage disk drives.