If the problem is similar to the one I’ve been experiencing, you get the normal screen that presents the option to deploy image, register host etc etc, then when you chose the option to register a host, the white background disappears and the continues a normal boot from the virtual disk.
The guide I was following to set it up mentioned that FOG wouldn’t capture from UEFI.
After building my Win10 image (tried with 1903 and 1910) and getting the same problem I found took a different approach. Build the Windows system, sysprep it. Before booting again, change the system type from UEFI to BIOS (as we’re not booting Windows it won’t matter). Then registered the host and reboot to capture the image.
Only thing I found was that when I restored to another VM it had to be set with the virtual disk attached as SATA not SAS.
The guide I followed which mentioned the issue about UEFI capture is below.
https://www.ceos3c.com/sysadmin/create-generalized-windows-10-image-deploy-fog-server/
Running Fog 1.5.7 from a Centos 7 host, ESXI is 6.7u3