The Symantec Endpoint Protection 12.1 (SEP) client does not run LiveUpdate on the specified schedule. When run manually, LiveUpdate runs and downloads content as expected.
The SEP client checks for a valid, idle network connection before running a scheduled LiveUpdate. When a computer's network connection is configured either without a default gateway, or with a default gateway of 0.0.0.0, the SEP client will be unable to determine the idle state of the network connection. Since the network connection does not appear idle, the LiveUpdate session will never be initiated.
This issue has been resolved in SEP 12.1.6. Please upgrade affected SEP clients to resolve this issue.