I think it can happen if AppleACPIEC hasn't attached yet? Possibly? I'm not quite sure tbh.
It seems ACPIEC is not working.
I tried manually patched the DSDT,and got following error:
ACPI Error: Result stack is empty! State=ffffff902d6d0810 (20160930/dswstate-182)
ACPI Exception: AE_AML_NO_RETURN_VALUE, Missing or null operand (20160930/dsutils-775)
ACPI Exception: AE_AML_NO_RETURN_VALUE, While creating Arg 0 (20160930/dsutils-902) [ECRD] @00015 #0070:
Local1 = -Return Value- ()
Local0: ffffff902cfde640 <Obj> Integer 0000000000000000
Initialized Arguments for Method [ECRD]: (0 arguments defined for method invocation)
Arg0: ffffff902cfde2d0 [RefOf] <Node> Name LSTE Uninitialized
ACPI Error: Method parse/execution failed [\_SB.PCI0.LPCB.H_EC.ECRD] (Node ffffff99c6abf3c0) , AE_AML_NO_RETURN_VALUE (20160930/psparse-632)
ACPI Error: Method parse/execution failed [\_SB.PCI0.LPCB.H_EC.LID0._LID] (Node ffffff99c6abe690), AE_AML_NO_RETURN_VALUE
Looks like EC fields are not read at all.