Did you get any resolution for this problem?
I have Fog 1.5.7 on CentOS 7 with the specified partition sizes. All other settings as default, firewall and SELinux are disabled. My image name is W10E.
I get the same results as you did, also with the image files appearing in the /images/dev folder, then in /images/W10E and then disappearing again.
I sort of got around it by copying the /W10E folder to /W10E (copy), wait for /W10E to disappear and then rename the copy as /W10E. And I can deploy this image, absolutely no problem.