I'm thinking Windows 11 downloaded updates/patches about the same time I installed Bitcoin Core v25.
In a pinch, I can use a separate Windows 10 server for Armory, but that's an old PC I'd like to use it for other purposes.
Windows 11 is my fastest PC, so if I can figure out this problem, it would be awesome.
If you think that it's the cause of the issue, then try to uninstall the latest updates of your W11 machine.
Refer to this article to see how:
support.microsoft.com/en-us/windows/how-to-uninstall-a-windows-updateThen, since you've already downgraded and confirmed that you have the complete blockchain but the issue remains, then we can deduct Bitcoin Core out of the suspects.
Today I reset Windows 11 by running the built in Windows utility to deinstall all programs completely including Windows 11. I chose the option to download the Windows 11 installation files from the Internet, and I also chose the option to keep my personal files and folders. After that, I reinstalled Bitcoin Core 25 and Armory.
Summary: I get the same Armory result with "Scanning Transaction History" hanging at 43%.
The nice thing is Windows 11 starts a whole lot faster now!, so it wasn't a lost cause.