RiskWare.BitCoinMiner Malware - did not detected by Endpoint 12.1.6

Hello,

Symantec Endpoint Protection is working on one of our Windows Server 2012 R2, and our server has been hit by RiskWare.BitCoinMiner Malware and eating all CPU. I run full Symantec but it couldn't detect this malware... I download one more malware program that prompty detected malware and delete it.

our Symantec version is:

Symantec_Endpoint_Protection_12.1.6_MP8_All_Clients_EN 

I will apprecaite any possible support to know why Symantec didn't detect the malware ?

Thanks