This bit of your answer is why I upvoted it: "everyone should note that as written, these procedures are for Windows installed on a MBR disk (ie. not for Windows installed onto a GPT disk on UEFI hardware)." Indeed, even the answer mentioning "VHD GPT-disk" first converts VHD to MBR as there is no way that
DISKPART will let you make any partition "Active" on a GPT-disk. When you have a GPT disk, follow the steps insuperuser.com/a/1444266/14061 by @Nathan2055