Cannot change cover image

Hi there, I seem to be having some difficulty with the cover image feature of the DW Timeline theme. I’ve tried to change the cover image, but nothing seems to happen. I go to upload the image, and I see no change; what makes this kind of weird is, the image itself actually gets uploaded, but I cannot seem to change the image in the Cover Image part of the Customize option.
I haven’t been able to figure out if this is a theme issue or an issue with my hosting, so any help would be much appreciated.