Header Image Changed After Update

In early January there was an update to the free Hestia theme. After the update my Header Background Image had been replaced by what appears to be the default image: the Statue of Liberty. Since then I’ve tried in vain to change it back to my custom image. I have been hoping the problem would be caught and fixed but after the last update I still have the problem.

The page I need help with: [log in to see the link]