I may have spend some time on this one. Roughly based on Southampton, the town I live in.
Just attempted it for a fourth time - again, the Preview in small, the full in Detailed - the preview stays and the larger one just disappears. I don't think I can submit my art, something keeps breaking on it.
I didn't though, I edited it three times now to add the larger version into "Detailed" and the smaller into "Preview". The Preview submits, the Detailed just disappears.
You probably uploaded it wrongly.
For some reason it won't let me attach the full version - perhaps it breaks something? It's 500x1000 pixels in size altogether :T
Did you mean for the preview to be the main as well? I really want to see more, Its so beautiful!