Mask reverses when printed

Hi! I have never had this problem in illustrator, but on my computer, the mask is set correctly, then reverses itself when it is printed. The first picture is the artboard and I would like the document to print, but it prints as the second photo. There is even a strang mask showing on the side. Any ideas on what I have done wrong? Thank you in advance, not often I run into something that takes a forum to solve on illustrator!