Updates not installing without asking

Hi

We're setting our windows update settings through group policy.

I've set the auto updatepolicy to

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4 - Auto download and schedule the install

And the scheduled install time is set to every day at 1pm.
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However, on our test machine when I go to shut down my PC I'm getting the
"Install updates and shutdown" prompt instead of the updates installing
themselves.

Is there any way to fully avoid this and just have windows install the
updates itself? We really want to remove any user influence on the update
process.

Thanks for any help
gerryR