Are the disks configured in a raid configuration and the firmware is in UEFI mode? If so you are probably out of luck. There is a known condition between Linux, UEFI, Dell computers with the hard disk controller in the “raid-on” mode. Understand this is not a FOG issue (exactly), but a Linux - Intel-Raid driver issue.
If the disks are not in a raid configuration, then switching the disk controller back to ahci mode will allow you to capture and deploy using FOG.