Header image disappears

Is there a known issue with header image? I've downloaded the free template and the header image disappears. Thinking that it was just the free template, I tested your demo and the header disappears too. The green image displays when the demo loads. However, after a few refreshes, it just disappears. I'm considering buying the template but I need to know that you have a fix or update. Please advise if there is a few or update. Thanks, LaTanya