When I export my .ai file as a bitmap, Illustrator adds a 1px wide column of blank space on the left side that I keep having to crop off. I can't figure out why. I even deleted everything else from my file except the colored background that takes up 100% of the canvas and is positioned at 0 X & Y... but my 1920px wide file still exports as a 1921px wide bitmap with an empty pixel on the left. Does anyone know why?
Check your document settings and pixel grid alignment. Set it to 72DPI.
I have exactly the same problem. A 1px transparent margin is added to the output PNG. As I have set up a complex doucument with various artboards this is a serious problem for my workfow. However only few artworks are effected. The hint by Mylenium did not help, as my document was already on 72dpi. I guess it is a bug.