@2097 thanks. Yeah, that's what I ended up having to do. Not a clean solution really as it could break in future, but for now, until Microsoft fixes their stuff(!), it works. Thank you.
Mid of January 2026 now and still not able to get this to work using a GPO and Windows 11 Pro 25H2. Incredibly frustrating. As others have stated, the GPO for device level json does nothing, and the GPO for users level json breaks the Start menu and stops it from showing up when clicked.
Has anyone made any progress? Would be happy even if it just applied once to each profile but can't make anything work unfortunately.
Here's our Windows 10 logon user script which we push out through group policy. Hope this is helpful to others...
rem ###Script to migrate and symlink Outlook Signature to OneDrive###
if not exist "%userprofile%\OneDrive" goto done
if exist "%appdata%\Microsoft\Signatures\DoNotRemove" goto done
echo n|xcopy "%appdata%\Microsoft\Signatures" "%userprofile%\OneDrive\Documents\Outlook\Signatures" /E
md "%userprofile%\OneDrive\Documents\Outlook\Signatures\DoNotRemove"
cd %appdata%\Microsoft\
ren Signatures Signatures-OLD
mklink /d "%appdata%\Microsoft\Signatures" "%userprofile%\OneDrive\Documents\Outlook\Signatures"
:done
Aaargh! Have just spent hours on this too, same situation, exported WIMs and using the unattends from 2008R2 on WDS 2012 R2 and it just won't apply the unattend.xml on the PE boot environment.
Anyone have any ideas?