Yesterday was Patch Tuesday and Windows 10 V1709 DID update to 16299.371. No issue.
But if I run Updates again, all done - nothing to update.
I went to the Media Creation Link and run Upgrade this PC. That puts an icon on my desktop and it tells me I have the latest version. I did that yesterday and I have tried it every 8 hours ago and nothing.
So no V1803 yet except for Insider machines (yes, I have it installed on my insider machine).
In the registry at Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services, is shadow present and set to 2 or 4? That means, your pc might be setup for shadowing without user consent, which mirrors your screen, without you even knowing it.