https://www.bleepingcomputer.com/news/microsoft/windows-10-kb4520062-update-may-break-microsoft-defender-atp/

Microsoft says that Microsoft Defender Advanced Threat Protection (ATP) might stop running on Windows 10, version 1809 devices after installing the KB4520062 Cumulative Update.

The non-security KB4520062 optional update was released on October 15 and it is designed to fix an issue leading to black screens being displayed at startup during the first sign in after installing an update.