I have a theory why it's not working: I followed these instructions and I get
code:
The following sleep states are not available on this system:
Standby (S1)
The system firmware does not support this standby state.
Standby (S2)
The system firmware does not support this standby state.
Standby (S0 Low Power Idle)
The system firmware does not support this standby state.
(S0 corresponds to Modern Standby.)
I don't think I care about actually using Modern Standby, but I do want to enable device encryption. Has anybody gotten this working?