After an update is released for Symantec Endpoint Protection Small Business Edition (Cloud), the agent doesn't automatically upgrade if the user on that machine is not an administrator.
On desktop operating systems no error will be seen, on a server OS a popup may be seen asking to log in as an administrator to complete LiveUpdate.
The upgrade will only take place once an administrator is logged in as admin rights are required for the upgrade to complete. Please log into the machines as an administrator to complete the upgrade. Alternatively, uninstall the agents, reboot, and then deploy the new version via a redistributable package.