TL;DR: PowerShell fix worked for me after 24 hours.
Had the same with a fresh 1709 install, tried the powershell command multiple times to no avail ( it would usually give errors in the end that it...

I've read your reply, and just to update, my solution didn't stick for me either - shortly after the main PC stopped going to sleep again.
So I might end up overriding the process or just ignore it.

Hey Xilnik, I don't know if you're subscribed to this, but thought I'd add my two cents.
I've encountered this "not going to sleep" issue for years ever since I started using homegroups, and it has...