Windows 10 build 20270

Windows 10 build 20270 is the twenty-third Insider Preview build of Iron, the 21H1 development semester of Windows as a service. This build was released on 3 December 2020 to all Windows Insiders on the Dev Channel. Three days prior to this build's release, a screenshot was shown of this build by a Microsoft employee on Twitter.

Changes

 * The Advanced View feature for Drive Optimizer, which was added in build 20241.1000 but was broken, 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 in Windows Feature Experience Pack build 120.2212.1070.0.
 * The timebomb was extended from 31 January to 31 October 2021.

Bugs

 * The update process to this build has a chance of hanging for extended periods of time.
 * Live preview doesn't work for pinned site tabs on some machines, a gray window is seen instead of the intended content.
 * There's a chance of encountering an error with the error code 0x80070426 when using a Microsoft account to sign into certain apps. If this bug is encountered, it can be usually fixed by restarting the system.
 * The modern Disk Management page located at Settings → System → Storage → Manage Disks and Volumes is completely blank, and as a result it will not display any drives present on the system. To workaround this issue, use the legacy Disk Management tool to manage disk drives.