Updates that would normally have high applicability numbers are not showing as applicable to a large percentage of Windows 7 and 2008 computers in the Patch Management Software Bulletin Details report and are missing computers in the Compliance reports. This may be seen in all environments, regardless of Symantec Endpoint Protection being installed or not (see TECH255917.) 

See TECH255917 for more details; detection logic was suspended temporarily

Run the PM Import task and verify it is on version 7.3.393 (released on 9/4/2019)  or higher, and allow time for clients to run another Windows System Assessment Scan