When a third party anti-virus/malware solution is installed with Windows 10, Windows Defender normally is disabled to avoid any conflicts. With the Anniversary Edition of Windows 10, a new option is available to allow Defender to perform a background scan.
To enable Limited Periodic Scanning, open Windows Settings and Update & Security. Access the Windows Defender section. If Windows Defender is currently the default security client, the following menu option will not be present.
A system tray notification will appear if the feature is enabled.
Additional details on this feature can be found at https://blogs.technet.microsoft.com/mmpc/2016/05/26/limited-periodic-scanning-in-windows-10-to-provide-additional-malware-protection/