Pam - It's been a while since I used the Tri-Rec, but I think I had to keep moving my needle over to get the correct finished size. I am using the Accu Quilt for this mystery and even with that, I am moving the needle over more than I normally would. I am sewing on my HV Topaz 50 and using a quilting foot. With the 4-patch, I moved the needle over 1.8. And with Clue 2 and 4, I moved the needle to 2.5.
Maybe it's just something with the shape of the pieces. ?