Guys just to update we have had a successful build. It turns out if you delete an img directory in the source to remove any source changes the storyboard images need to re-set.
That is go to App Settings and browse the images to ensure they are linked to an image in your library. My Story board images were in the media library but were not linked when I pressed Browse. To fix I clicked on the image and clicked Apply. On save, the images are put back in the img directory. (Note you may need to close your project and re-open to see them.
Note From Illia
"Re-set all the images in your project iOS settings, the build server doesn't see a file in Storyboards. Keep in mind that the image file should be without any transparency."
One very happy programmer.
I still think access to some form of error messages in the build process is a great suggestion from Bruce.