In our environment if I fetch Computer status log it shows nearly 50% of clients sequence number as 0.But all the clients having latest definition.
Note: It displays 0(Zero), not blank.
SEPM Server version - 12.1 RU6 MP2
Clients - 12.1 RU6 MP2
I don't believe this sequence and definition have any direct correlation. I have this same thing and the sequence number is different on many nor is it indicative of a date. I would focus on the definition date here.
Today we faced one issue, a virus file was not captured by a machine having latest certified definition, so we submitted the file to security response and they replied that this file will be captured in two months back sequence number definition so we checked the sequence number in the client it shows 0.
Then we'd need to understand where that number is being pulled from. I have clients with that latest content and checking to the SEPM who's sequence number shows 0 in the computer status log.