After upgrading MAC to OS X 10.11, SEP cannot update. Does SEPM 12.1.2015.2015 supports MAC OS X 10.11? Liveupdate policy is as attached screen and schedule frequency is set to continuously.
MAC to OS X 10.11 does not support SEPM 12.1.2.
Below are mac support
System requirements for Endpoint Protection 12.1.2 and 12.1.3
https://support.symantec.com/en_US/article.TECH195325.html
SEP 12.1.6 supports Mac 10.10. This is the highest supported version by SEP at current: