@ombreit I think one of use is confused. I will raise my hand here.
The normal process is to:
Create an image definition in the FOG Web UI. PXE boot a source computer and register the computer with FOG. The source computer will be used as your golden or master image. You will then in the web ui connect the new computer with the imaged definition. In the web ui you will then schedule a capture task. You will pxe boot the target computer and capture or upload the golden image to the FOG server.When you do step 5, in the picture you last show, the image size on client value will be set. The picture tells me you have not uploaded an image yet to the FOG server.
Also from the picture you gave us with lsblk the source computer does not have an image on the disk. So there is nothing to upload to the FOG server.
So I don’t understand where is your golden or master image coming from?