E-series scan to SMB login error with Windows 10

[Motormount]

Here's a good one:
Setting up a lease-return C284e in our demo room, I attempted to scan to SMB to my Win 10 desktop: login error. Remembering Win 10 is peculiar about the login, I tried every combo I could with no luck.
We have a C253 we use for office stuff which was already set to scan to my PC; it still scans to my desktop fine. So using PageScope Data Administrator, I copied my address over to the C284e - still login error.
I get my Win 10 laptop, configure scan to smb to it from the C284e, and it works.
Using Data Administrator I copy another address from C253 for a Win 7 PC over to C284e, and it works.
I check Norton firewall, turn it off, still login error from C284e.
I unplug Ethernet from C253, change IP on C284e to match C253, still login error.
Edit: I just remembered that I haven't turned off my PIN login. however, I did try using another user's login on the same PC with no luck. I'll check that and get back.
I turn off IPV6 on C284e, no change.
I set another lease return C364e to scan to my PC - login error.
I tried changing SMB settings on the C284e, but no help there either.
WTF?
Now, both of the lease returns were wiped (Admin mode, overwrite all data) and I checked that there are no remnants in the network setup. Besides, it works to the Win 7 PC.
My PC is the free Win 10 upgrade from Win 7; my laptop is the free Win 10 upgrade from Win 8.1. All are Pro, 64-bit versions. All I can figure is something screwed up in the Win 7 to 10 upgrade. But why will the C253 still get in?
Oh, and I cannot browse to my desktop from either the C253 or C284e - it's rejecting my login credentials.
I'm wondering if anybody has run into this before, or has any ideas to try. First, I do not want to do a clean install on my PC again (I just did one a few months back due to HDD failure). Second, I'm sure some client sooner or later will upgrade to Win 10 from 7 and I'll see this again.
Your input is appreciated!

[Motormount]

Heh. Like I always say, when you get stumped on a problem, go have some lunch.
It is weird, though: the C253 uses my Microsoft Account email login and works fine. The C284e uses my old local ID, and the password I created for the Microsoft email login. Go figure.
Like Rosanna Rosannadanna used to say, "It's always something." "Nevermind" also comes into play here.