It isn't a model issue. It's an efi / legacy issue. Your original image was legacy so when it's deployed, Theopenem configures the machine for legacy to match the original. But since it's an efi machine that's not going to work. Setting the partition method to standard tells Theopenem to ignore the original image and match the destination machine type. That's how a single image can be used for both efi / legacy, using the standard partition type.
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