Try re-registering Liveupdate with SEP by following the commands:
Open cmd -> in D:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\bin
- Type lucatalog -cleanup and press Enter.
- Type lucatalog -forcedupdate and press Enter.
in C:\Program Files (x86)\Symantec\LiveUpdate start luall.exe (execute with local admin rights)