Did the same thing to me...I deleted the first attempt, worked just like it was supposed to the second time around. Then I wanted to edit description, pic disappeared. So I re-edited, pic was there.

I do not understand how this happens. When you enter the url for your site, it's supposed to make an image of your front page automatically. I cannot create this error with any reliability. There should be an image of your front page in the box above.