Microsoft resolved a known issue causing Microsoft Defender Advanced Threat Protection to stop running and fail to send reporting data on some Windows devices after installing the KB4520062 optional non-security update. Microsoft also fixed two other known issues introduced over five months ago, causing abnormal battery drain and update installation failures issues on Windows 10 1903 devices. These issues were fixed on the same day the Windows 10 November 2019 Update started rolling out (also known as Windows 10, version 1909) with feature improvements and bug fixes.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-fixes-windows-10-1809-issue-that-broke-defender-atp/