There is a couple of things that could be the problem/solution.
First, while its not a problem here, ensure that secure boot is disabled
In regards to raid.
In fog configuration -> fog settings click on the expand all button. Search for kernel args and add in
mdraid=true. Save the settings.
What this does it tells FOS linux to enable the raid management drivers in the kernel. If you are using the built in, intel rapid store raid you will need this kernel arg enabled. The intel raid, is a hardware assisted software raid. To linux it will present both the physical drives as well as the logical array. Since you are not seeing the nvme disks, this is probably not your current issue but there is no harm to have this feature enabled.
What I want you to do next is manually register this 3420 and schedule a capture or a deploy (doesn’t matter) but before you schedule the task tick the debug check box then schedule the task. Next power up the target computer but hit F12 a couple of times as soon as you see the dell logo, we want the boot menu to appear so we can do the next test. When the boot menu appears select from the bios menu (not uefi) network boot (if no bios boot options go into the firmware settings and enable legacy roms then reboot). We want to pxe boot the target computer in bios (legacy) mode. There is a known issue with Dell computers with the disk controller set to Raid-On and uefi mode. By booting in bios (legacy) mode we will be able to bypass this known issue.
When booting in debug mode you should see several screens of text that can be cleared by pressing the enter key. After pressing enter a few times you will be dropped to a linux command prompt. At the linux command prompt I want you to key in
lsblk and post the results here. This will show us the disks (block devices) that linux sees in this computer. You can either key in what you see here or take a clear picture of the output of that command with a mobile phone and post it here.
Once we know what we see in bios mode we can guide you to the next steps.
FWIW I imaged a Dell Precision 3630 last week (with sata drives) with the disks in a raid configuration and I had to switch to bios mode for imaging but the windows image and final firmware settings are uefi. Meaning you can image a uefi computer just fine in bios (legacy) mode even if the final operating mode is uefi.