...also, does Secure Boot have any effect on this?

Changed the language to EN-US in UIFallbackLanguage. Ran another test. Still giving me flak about a problem labeling a partition. I have to assume the issue is with something other than the actual...

Ok, here's my autounattend. The good news is I've confirmed the other half is working as intended; basically if I strip out this one and do the initial steps manually, the rest goes on its own. But...

Hello, I am also having trouble with the first stage of this, the Windows Setup. When I use the steps, I get the following error:
"Windows could not assign a volume label to a partition on disk 0. ...