sorry if this question is already answered, i could't find it.
Why while exporting with artboards, this happens? I use artboards, and this artboard is 900x1600 (not 894x1600). Making all layers exact size as artboard size is really not the way... especially that other group of layers work's correctly. If you have 10 banners with five sizes, it's really big work to fix everything.
Making canvas size 900x1600 is not an option, because it leaves white gaps.