I am trying to find technical document.when i will found provide you.
See Symantec employee Chetan comments
https://www-secure.symantec.com/connect/forums/sepm-dashboard-not-updated
See Rafeeq comments
https://www-secure.symantec.com/connect/forums/risk-found-scan-log-not-virus-risk-activity
Edit
You can check time range if this is issue.
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