The latest version is 12.1 RU2 so you're still 2 versions behind.
Looking at the release notes for 12.1 RU1 MP1, I found this:
Bugcheck 9F (DRIVER_POWER_STATE_FAILURE) references SYMEFA64.SYS
Fix ID: 2636799
Symptom: The SEP client experiences a blue screen with bugcheck 9F (DRIVER_POWER_STATE_FAILURE). The blue screen references faulting driver SYMEFA64.SYS.
Solution: The SymEFA64.sys driver was modified to prevent this crash.
So you can either upgrade to 12.1 RU1 MP1 or go right to 12.1 RU2. I would suggest upgrading to 12.1 RU2.