I suspect being able to visualize something feels so natural to you you have a hard time imagining it could be otherwise. However, for folks like me it just doesn't happen.

When I dream I see the dreams just fine (so I think I understand what it is to have a minds eye) but can't reproduce any remotely similar thing while awake. Imagining sounds works fine and occurs not in my "real" hearing (so I get the distinction you're talking about with visual imagination) but with vision there's basically nothing for me.