Please check whether latest wsusscn2.cab file is downloaded in SapphireIMS Server repository and if not, check the CAB file download configuration. Please refer our online help link Windows Patch Management Settings
Patch scan should use latest downloaded wsusscn2.cab file to find latest released KB articles missing in target machines.
Genuine Case: KB itself might not be released in the latest wsusscn2.cab file and this can be tested with third party tool (Windows Update Mini Tool) using offline mode with downloaded wsusscn2.cab file.