Update not following instructions to update at 3 AM

I have Windows Update set to install updates automatically every day at 3 AM. Yet, it keeps interrupting me during the day with a window that says it will perform the update within a few minutes unless I postpone it. I don't want to be interrupted during the day, I'd like it to do what I have asked it to do and update at 3 AM. I thought it might be doing this because the computer was asleep or hibernating at 3 AM, but the help on this topic explains that Windows will wake the computer up to perform the updates as long as it is connected to a power source, which it always is.

Can someone please tell me how to set this up properly?

Thanks you.

PeterPSA said:

...Windows will wake the computer up to perform the updates...

That does not always work. Take a look in the System log entries. See if there are entries around 3am.

See this post if you need help finding that log:
wake-on-lan activated : computer keeps waking up by itself


Another test would be to change the Windows Update time to say 2pm. Manually put the computer to sleep and watch to see if it wakes to check for updates.