For some reason, when I play it the background is black.
Though it's not black in the editor.
Here is the capx: dl.dropbox.com/u/75406771/black.capx
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I don't think this is a bug: you have an object which has an image sized 10,000 x 1080. This *far* exceeds the maximum supported size which is 2048x2048. If you delete it, it works. I'm afraid you simply need to design your game to use smaller images, there is no way this can be supported.