Its still not clear if this is a fog problem (which I’m thinking not) or a reference image creation issue. Of course you would have a snapshot before you sysprep (so you can restore the vm after this test), but sysprep the image on your reference image and then just boot your reference image back up. Does it startup without issue? This will test without fog in the picture. You are just syspreping the reference image and then booting it up through OOBE.
As for the logs in panther, they end with .log as well as there is a folder with DG or DC in the name there are logs in there too. You may have to copy them to the desktop to be able to view them. But they should give you an idea of what is going on with the OOBE process.