A bug in what appears to be the Microsoft Windows activation service is causing Windows 10 Pro licenses to be downgraded to Windows 10 Home and then stating that Windows is not activated. This happens in Japan, Korea, American and many other countries. Jeff Jones, Sr. Director, Microsoft., told BleepingComputer in a statement: We re working to restore product activations for the limited number of affected Windows Pro customers s activation server at the moment. Affected customers will see resolution over the next 24 hours as the solution is applied automatically.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-bug-is-deactivating-windows-10-pro-licenses-and-downgrading-to-home/