@El_Pagrxn27 I guess I’m doing a terrible job explaining what I see.
If we refer to the picture you provided. You see /dev/sda is exactly as you say the 1TB hard drive connected to sata5. Also you see that /dev/sdb is exactly as you say the 256GB drive. Now what I’m saying is the partition layout for both the 256GB and 1TB drive are exactly the same. So something happened here. I would expect /dev/sda3 to be ~900GB in size, not 256GB unless this is how its configured on the source computer. I would say the layout that is on /dev/sdb is a typical windows boot image format.
disksize.png
I’m suspecting some how the image for disk /dev/sdb was overwritten onto /dev/sda. This is why the target computer will not boot.
While I understand this is how your fleet of computers are currently setup, the configuration is a bit uncommon. The more common approach is that the boot/OS disk to be on /dev/sda (i.e. lowest sata port number) and the storage disk to be on some sata port number higher than /dev/sda (5 in this case). Now understand that it is possible to have the OS disk setup like you have it and work, but FOG may be making an assumption that you have a default design. I don’t know this bit yet. Right now I’m having a hard time understanding why both disks have exactly the same partition layout.