Configuration Profile - Software Update applied, com.apple.softwareupdate.plist not updated?

some more testing.. and the setting in the config profile reflects in the software update advanced, but don't reflect in com.apple.softwareupdate.plist

The setting IS reflected in /Library/Managed Preferences/com.apple.softareupdate.plist

I have a device the despite the setting to not download and not install, the /Library/Preferences/com.applesoftwareupdate plist is set to ON and ON.. and so attempts to download and install..

I think you've figured it out, but I'll confirm. Applying a configuration profile doesn't alter the local computer or user plists. Their settings override the plists when applied. When the profile is removed, the settings from the original plists come back to life.

The plist you've found in '/Library/Managed Preferences' is indeed indicative of the profile being installed. Many applications also reflect the profile's settings by dimming the options being managed. If you apply a profile for Software Updates, you should see you can't change them.

Looks like you are on the right path. /Library/Managed Preferences is where preferences set by an MDM would go. These have precedence over anything set in /Library/Preferences which is not a managed directory.

If you needed to deploy a plist to /Library/Preferences for some reason (like with webex... ... ...) you would need to package up the plist and deploy it with a policy. Dont do this unless absolutely necessary but some applications (like webex... ... ...) dont respect /Library/Managed Preferences.