The recommended method to convert these disks is to upgrade the operating system to Windows 10 first, then perform the MBR to GPT conversion. So 2k8 sounds like a no no even for an offline conversion.

MBR2GPT.exe will convert a Windows 11/10 computer from legacy BIOS to UEFI disk partitioning. Convert a disk from MBR to GPT partition style.

For added security, Windows 11 will forgo the older MBR partition scheme and use GPT instead. That may require users to convert their older hard drives. Here is how to do it.

Doing so causes the GPT partition table to overwrite the data on the destination drive. To resolve this issue, the user needs to convert the GUID Partition Table disk to MBR.

Then, right-click the MBR disk you want to change to a GPT disk and select Convert to GPT Disk. What is the number of partitions that the MBR partitioning system can support?

Can anyone shed some light on whythe Ubuntu 18.04.1 installer can't see any partitions on the NVMe disc (so I can't add a new partition after the existing ones) but if I hit ctrl-alt-F2 to get to ...