After upgrade of the client software, Symantec Endpoint Protection (SEP) for Mac no longer updates Network Threat Protection (NTP) definitions.
NTP definitions may show as Not Available or "N/A" as per screenshot below:
SEP for Mac
Reboot the system and if that doesn't resolve:
1. Open Terminal
2. Run command: sudo ls "/Library/Application Support/Symantec/Silo/NFM/Sett
3. Make note of all files with filenames com.symantec.ips.* where * could be numbers from 0 to X.
4. Delete all aforementioned files by running following command for each file: sudo rm -rf "/Library/Application Support/Symantec/Silo/NFM/Sett
5. Restart the system and run Live Update
NOTE: It may render system unstable. If the product behaves unexpectedly please reinstall SEP.