Hi,
Reinstall liveupdate & check.
Repair your SEPM also.
What happens when you run liveupdate manually i.e go to start--> run --> type "luall.exe"
Do you see any error after running luall.exe manually.
If possible please share show liveupdate downloads screen shot.
You will find at following path
SEPM Console --> Admin --> Servers --> Local Site --> Show liveudpate downloads
Jdb file will update only antivirus and antispyware definitions only , but it can't update PTP (Proactive threat Protection) & NTP (Network Threat Protection) definition