Content not displaying in Responsive HTML5 Output

I inherited a few projects, copied all project files over to my machine exactly as they existed on the previous writer's machine, but when I go to generate the output, the main content window is blank, and when clicking a link from the TOC on the left, the content flashes briefly, but then the screen returns to just the frame with no content where it should be. Attaching screenshot. As a note, one of the 3 projects I inherited generates fine, while the other two do not. We've investigated everything that has occurred to us that might impact this, but when the previous writer generates the output with the project files I send her, it generates fine. Help! Projects were created in Robohelp 2015, which I am also running.