You install a security update to an endpoint and no restart occurs at the end of the Software Update Cycle. You may have configured the Software Update Configuration Policy to not reboot the endpoints at the end of the Software Update Cycle. You notice the Windows Compliance by Computer Restart Status and the Restart Status reports initially show the computer as Restart Pending 'Yes', and the computer is in the Restart Status report. Unexpectedly the status changes to Restart Pending 'No' and is no longer in the Restart Status report. The problem is that the computer did not restart.
PM 8.x
Policy was disabled or removed from targeting the specific endpoint.
This is working as designed.
If there is a policy which installs an update, and you disable the policy or the security update is superseded, this behavior will happen. The security update may become superseded and if the Patch Remediation settings are set to Disable Superseded Updates, this can happen.
Best practice is to reboot the endpoint when you install the security updates. Don't install security updates when you unable to reboot if a reboot is required.