I haven't done that pattern but I've made several X-Blocks quilts and haven't had any trouble. Are you using the right size template for the pattern? There are both 6-1/2" and 7-1/2" X-blocks templates, each requires you to cut different sized strips. Maybe you need the other size?
I have the pattern at my shop, and a sample quilt that someone else made for me, when I go to work tomorrow I can look at it and see if I can figure out the problem for you.
Andi