Microsoft Released Windows Server 2019 and 10 version 1809 Redstone 5 on October 2, 2018, with Improvements and new features. 1809 release considered the sixth major release of the operating system, and it’s also the second semi-annual update of 2018.

Today I was trying to Download the latest ISO from Volume Licensing Service Center (VLSC), but I found the following Notification

Users report losing of their documents after Update or Upgrade, but if you want to upgrade do it in your own Risk.

Known issues are documented here.
Hope this helps, and Microsoft fixes it ASAP.