In some cases it is necessary to send or resend the Patch Reboot event. The Patch Management compliance compare the patch installation event from the Inv_AeX_SWD_Execution_Summary and Evt_Reboot tables. If there is no reboot event post update installation that requires a reboot, then the update with be treated as not installed/vulnerable. This affects the compliance level/percentage of a given bulletin.
Pick a test PC with false compliance levels and set this in its registry: