I can't scroll using my mouse wheel on some books

I noticed that some books do not scroll using the mouse wheel, unless the mouse is hovering over the navigation bar at the bottom of the screen.
It's really annoying since it only happens with some books, and I need to either reach for the keyboard to scroll, or hover my mouse at the bottom of the page, every. single. time. I have to scroll.
Is this a bug?, do I need to submit a bug report?!