When I populate the fields in the Advanced options of the Create Boot Image GUI in SDK and run the image, all of the options are removed when re-entering.
This is a known issue. For the GUI, it will be addressed in a future release.
As a workaround, users can manually generate a .BIF file for BootGen.
The file can be used by importing it into the Create Boot Image GUI or by running BootGen from the command line.