windows – The unattended file is ignored after updating WIM via VHDX

I feel like I'm going crazy. I have done it a million times before and now it does not work anymore.

I'm trying to update the wim with the new SCCM client (because it's a nested WIM file in a server deployment), as well as to update the Windows updates .

I have an Unattend.xml file that includes the server name and the IP address and the process below works with the help of one of our existing WIMs.

  1. Create the VHDX from the WIM:
Convert-WindowsImage -SourcePath "E:  path  VMWIM.wim" -Size 100GB -DiskType Dynamic -VHDFormat VHDX -VHPartitionStyle GPT -VHDPath "E:  path  VMWIM.vhdx" 
  1. Mount VHDX for consistency check:
                Mount-WindowsImage -ImagePath "E:  path  VMWIM.vhdx" -Path E:  path  Mount -Index 1
  1. Create WIM:
                New-WindowsImage -CapturePath E:  TempVHD  Mount-Name VMWIM -ImagePath E:  TempVHD  VMWIMv3.4.wim -Description "Server 2012 R2 VMWIM" -Check
  1. Create a VM from the WIM above:
                C:  path  Convert-WindowsImage.ps1 -WIM C:  path  VMWIM.wim -Size 100GB -DiskType Dynamic -VHDFormat VHDX -VHPartitionStyle GPT -Unattend C:  unattend.xml -VHD D:  path  vmvhd.vhhx

When I do the above, the parameters Unattend.xml and Specialize (Name, IP, DNS, WINS) are all applied.

If I had to make changes to the virtual hard disk created in step 1, change the SCCM client, run the Windows updates, then run a sysprep with shutdown and continue with step 2. Once arrived In step 4, the vhdx file is created and Windows starts, but the specialize section is ignored (Name, IP, DNS, WINS). Even though I can see that the unattend.xml file has been copied to c: unattend.xml and c: windows panther unattend.xml (using exactly the same unattended file)

What am I doing wrong?