Help: I need to print on both sides (flip on long edge) but it is always off

Since I updated illustrator I cannot print on both sides flip on long edge because no matter what it is always off. Before I never had a problem and I was very pleased. Now, I do not know what to do, I make sure every mm and pixel is in exactly the same position on both artboards. However, when I print them they are way off I am talking about 5-10 mm off, that is ridiculous. What can I do to solve this issue? I want it like it was before.