I have found that when I update Mojave, using a simple policy to install and run the update pkg (e.g. macOSUpd10.14.4.pkg), the policy runs fine by installing the pkg and updating successfully, however the policy does now show as successful.
It looks to me like it is restarting to apply the update before the policy has finished, so it does not report back as completed.
it is not the end of the world as I can scope the policy to a smart group (e.g. MacOS 10.14.3) but it does mean I do not get the reporting back from the policy on percent completed.
I did not see this with High Sierra etc.
