In a blog post, Microsoft has confirmed the issue and the company has promised that a patch with fixes will be delivered in late January 2019.
Microsoft has also suggested customers to sign-in with the user administrative privileges other than the built-in administrator if they want to upgrade before the release of the patch.
If the PC has already been upgraded to the latest version and the built-in administrator is invalidated, the user will be signed in with administrator privileges other than the built-in administrator. In this case, Microsoft is recommending manual activation of the built-in administrator.
FLAC support issue
Windows 10 offers a full quality of uncompressed music playback with the native FLAC support, but in the October 2018 update (1809), the FLAC implementation is broken. Because of this, the music meta-data are getting decollated which results in unexpected issues. For example, the long names of music tracks and other music details are getting cut off.
The more frustrating part of this issue is when the tracks are arranged in a playlist, the music player will skip the first minute of the track and short tracks will be skipped totally. This happens in both Groove Music and Windows Media Player.
Microsoft hasn’t acknowledged the bug in Windows 10 update history page but the company appears to be aware of the problem as they have addressed the problem in 19H1 preview builds.