Build 21277 is out as an Optional Update

Been like this for quite a while & baffled me, too, for just as long.  Probably sounded like I wasn't wording something correctly or that I was misunderstanding something when I told it (here) initially. When something doesn't make sense, probably seemed like it was me not making sense 😉.

Regarding the IB:

That's why I'd said, it should be blurry when Not configured.  BUT it is not blurry. Nor is there a Reg entry for it.  What's the expression?... "Go figure" 😕 Oh & remind, when I noticed it wasn't blurred anymore, I had done nothing to cause that.  Remember, I was (pleasantly) surprised when I saw it.

"Who needs the "fog" on the logon screen ?" fg

Well, exactly... mine is NOT blurred, because I could never see the point of a blurry picture, and they are beautiful photos, too, plus only visible momentarily, anyway... may as well be able to actually know what you are seeing because it is not blurry.  Beautiful scenes are not meant to be blurry... it's why cameras & photos CAN be focused or even auto-focus 🤣📷  Why some folks were glasses... the world is not supposed to be blurry😂🕶

Cheers,

Drew

Very unusual, no explanation. Not aware of any other location in registry that could result in this. I tend to total clean install every IB and have always had to disable blur. Have never seen a build without since introduced.

Perhaps run a search in registry on your IB for "DisableAcrylicBackgroundOnLogon". Curious if there could possibly be another location, a backup of this key.

Regards,

Sure, why not, eh? (So) Did that & nothing or certainly, nothing new or different. In other words, found nothing. And, yes, I did wait until it was finished searching 😉 They mystery remains.  I haven't cared much... it made no sense, but they were both NOT blurred and I was/have been happy 😂.  Ain't broke, don't fix it... can't explain it, don't try 😂

Cheers,

Drew******

Not that this should have any bearing, are these two separate computers or dual boot.

Drew, 

On your IB could you try Enabling the policy and then check the registry after a reboot.

After that set it back to "Not configured" and see if anything changes.

I compared 20277, 21277 and 19042.685 and they all behave the same way on this "Acrylic" stuff. 

When the policy is set to "Not Configured"  the System key disappears completely.

Enabled:

Not Configured: