shot in the dark here but worked on one of my themes so may help with yours. Try setting the image you want to background-fan artwork. I found easiest way to do that is to go into regular launchbox, go to your game or magazine in your case. Right click to edit-metadata, scroll down the left-hand column til you find media>images. Then you can just drag and drop the picture into the menu, and it will populate, there should be a pull-down bar somewhere, and it would say something like boxes or front cover. Click on it and pulldown to background, then you should see more options and pick the fanart one. No guarantees that will work, but if you haven't tried that yet, wouldn't hurt.