Do you have Start11 installed, and if so, which version?
Yes, Start11 version 2.56, as well as Groupy version 2.3. (Big Stardock fan — thanks for keeping Windows usable, and thanks for the awesome strategy games!!)
Would you be willing to run (as Administrator) sfc /scannow ? I ask because I have 24H2 installed and have no problems and since you are absolutely correct regarding extensive testing by SD, and because system file corruption can always occur with wonky results.
Good idea, and indeed it did find things it wanted to repair.

I skimmed through the log and it seems entirely concerned with un-doing debloating (Xbox Gamebar, Windows Defender, SmartScreen, that sort of modern crapware). Here's the complete `CBS.log`: https://0.0g.gg/?a2ed8b12218dba94#CUJro9dH2gMLa51szenxWNNkH8iarHP4n4pv5KREUZhr
After rebooting, I ran it again to ensure it said it was happy, and it did:

After this, WindowBlinds showed me the “may not be installed correctly” message for the first time ever, and so I ran the Purge_WB script to get ready to re-install. Unsure if relevant, but both times I ran Purge_WB (today, as well as yesterday though I neglected to mention it) I got this message pop-up complaining about an entrypoint in WBCore.exe:

At this point (WB purged), I rebooted, reinstalled WB, rebooted again, re-activated WB with my serial and email, tried a Style again, but same problem as ever.
Just to be clear, you need to create a new local administrator account, there are lot of case where by simply create a new local Admin account and running it within that new local admin account resolved the issue.
Oh, my bad. You are correct that I did not create a new local Administrator account yesterday. I have done so now, did a Clean Boot (all non-MS services disabled, all startup items disabled, Start11 and Groupy disabled, manually started WindowBlinds Service), logged in to it and only it (not Fast User Switching with my usual account) but still same problem.
Here's the much shorter process list saved from Process Explorer while on the new local Administrator account, Clean Boot, WB Service manually started: https://0.0g.gg/?d1271cf49667210a#4mq1m9TNm41vHKgb9MGPtUyms3U5kHXz7ZbRChaChfKK
Here's a fresh video showing preconditions and unsuccessful testing on the newly-created account: https://www.youtube.com/watch?v=TaRt06jq-Yo
Something I forgot to mention when I was talking yesterday about the ways my Windows 11 installation is nonstandard: I also have the user profiles directory on a second partition, separate from the partition Windows is installed on. This is an official option, just one without a GUI, accomplished again using the `<ProfilesDirectory/>` key in `unattend.xml` file dropped into the root of my installer USB: https://www.tenforums.com/tutorials/1964-move-users-folder-location-windows-10-a.html
That example is `D:\Users`, but mine is `U:\Users`. It's the same NTFS as the C:\ partition and was formatted at the same time as the C:\ partition by the same Windows 11 installer.

I did this as part of my intended dual-boot setup: a small 256GiB (Windows) and 364GiB (FreeBSD, will be ZFS) partition out of my 2TB drive, and then the rest of the drive as a shared space for my personal files that can be accessed by both OSes.
I went with NTFS for the shared space instead of exFAT or ext{2..4}fs, because exFAT lacks support for Extended Attributes and all the other fun filesystem features, extfs is poorly supported on Windows (Paragon's package now even discontinued as of last month), FreeBSD's extfs support lacks journaling, and so NTFS native to Windows and via `filesystems/ntfs` on FreeBSD felt like it would be the least-worst solution. I'll find out in a month or so if I was right lol
I have not actually set up the other OS yet, because I'm waiting on the forthcoming final release of FreeBSD 15.0 due to substantial changes from 14 to the way the base system is managed [keyword: pkgbase], meaning I want to clean install 15.0 instead of upgrading from 14.3. This means the U:\ partition has only ever been mounted/read/written by this Windows 11 installation, never by any other Windows installation or by any third-party drivers.
Anyway I can't imagine that would be a problem; I'm just trying to think of anything and everything that could be unique about my setup compared to most peoples' typical Windows install. If you would like me to provide my entire `unattend.xml` I would be happy to do so, though will edit it to redact my legit Windows serial number and the password hash for my local user account.
I have re-debloated my system after writing this post, undoing the changes made by `sfc /scannow`, so if you would like me to repeat that before trying something else, please mention it 