I've finally managed to solve the problem, apparently away3D was using stage.stageheight and stage.stagewidth, instead of stage.width and stage.height. This resulted in the view using the width and height of my browser window as its size, not the swf size. After I swapped all references to stageheight and stagewidth to .height and .width it worked fine!
(I don't know why stageheight and stagewidth were used in the first place, but I'm sure there's a good reason for it)
