Content Analysis is not sending alerts because the failed update was due to network related issue.
There are two conditions in which Content Analysis sends alerts when pattern file failed to update:
1. Download is successful.
2. The downloaded pattern file failed to update the current pattern file.
If Content Analysis is unable to download the pattern file due to network error, it is expected that it will not trigger the pattern update alerts.
Monitor your Content Analysis appliance with an SNMP monitoring tool to be alerted to issues with connectivity, and take appropriate action to correct these issues. Failure to correct a network issue may also result in delays in processing user requests that pass through your ProxySG appliance(s).