Trusted Voice enabled, but unable to unlock screen

[HighfiveHeadache]

I've enabled the Trusted Voice option under General>Google>Search>Voice>OK Google detection, but it's not working. I've retrained the voice model and done a reboot, but the phone is not recognizing OK Google and unlocking the screen. I'm not sure if I've ever been able to get this feature to work on my S5, Lollipop or Marshmallow. I'm out of ideas and welcome any instruction, suggestions or help of any kind.