Out-of-date AV definition in SEPM but all clients receiving latest AV definition

Seems there is a reporting issue with SEPM.

All clients are reported as having out-of-date AV definitions in SEPM. After checking multiple machines, all of them had received the latest AV definitions. This proved that SEPM was still able to download the AV content from the Internet and distributed to all clients. Somehow the AV definitions information was not sent back to SEPM.

Ran Symantec Validation tool and confirmed SQL DB is in working condition and communicating to SEPM.

Rebooted SEPM and about 10 clients reported the correct information to SEPM within 5 minutes but this number stayed the same since.

Attempted to delete 1 client entry in SEPM, updated policy in SEP and SEPM reported this device as "not reporting status".

SEPM version is SEP11RU7, same as SEP.

SQL DB is on MS SQL server 2008.

Any help will be appreciated.

Thanks.