I don't know. Menu shutdown works for me, so I eventually just have different settings.
Please login by SSH, and open /storage/.kodi/userdata/guisettings.xml with the nano editor.
My power management section looks like this. Try the same settings:
Code
<setting id="powermanagement.displaysoff" default="true">0</setting>
<setting id="powermanagement.shutdowntime" default="true">0</setting>
<setting id="powermanagement.shutdownstate" default="true">1</setting>
<setting id="powermanagement.waitfornetwork" default="true">0</setting>
<setting id="powermanagement.wakeonaccess" default="true">false</setting>