unable to run step 3 of syspolicy_purge_history job on SQL Server 2012
Please look at this connect item

The SQL PowerShell wrapper SQLPS.EXE seems to execute a PS command Set-ExecutionPolicy restricted -scope Process -Force during its initialization. Then PS engine should then be initialized with command import-module SQLPS  -DisableNameChecking which is blocked because of the "Restricted" execution policy. This raises a critical error and the PowerShell engine terminates.

The workaround is adding/changing a registry key:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PowerShell\1\ShellIds\Microsoft.SqlServer.Management.PowerShell.sqlps110]
"ExecutionPolicy"="RemoteSigned"


See this and this for additional reference.