In the GUI, both "Install macOS updates" and "Install app updates from the App Store" are dependent on whether "Download new updates when available" is selected. It is important that a system has the newest updates downloaded so that they can be applied.
Solution
Run the following command to enable auto update: % /usr/bin/sudo /usr/bin/defaults write /Library/Preferences/com.apple.SoftwareUpdate AutomaticDownload -bool true Impact: If "Download new updates when available" is not selected, updates may not be made in a timely manner and the system will be exposed to additional risk.