This is the reason I threw mine out four years ago! I could cut straight fabric strips using a 24 inch ruler I got the shape cut ruler cause I thought it would be GREAT! It wasn't and I tossed it! Went back to using a 24 inch ruler instead.

I had the v problem using it too. I figured it out to work for me. The black lines on the bottom of the ruler above the slots has to be lined up even on both ends of the fold. If the bottom of the fold is on top or the middle or the bottom of the line on the right side it has to be in the same spot on the left side. When I get the measuring line lined up on the fold at the same spot on the line I then cut the straight edge and then start cutting strips. I don't cut more then two layers or I'll get the V.

I found that, especially after washing, my material it is a little wonky. By letting it find its natural fold (when folding selvedge to selvedge), its on the grain (then you can see how much its shrunk LOL). I just even it up and good to go. I've had this ruler for OMG many many years and if it ever broke I'd be running out to get another one.

Lots of people really love it, but I agree with you. I didn't like it at all.

I hold the fabric by the folded edge, not the selvages. Let it drape straight - may have to slightly move the fold side-to-side a bit. Selvage edges and edges where fabric was cut from bolt are not usually exactly straight. After finding natural even drape of fabric, I lay it on table, fold again, trim off fabric on left side (I'm left handed) using shape cut to square it up, then cut my strips - I really like my shape cut - & do cut through about 4 layers at a time, pressing firmly. Good luck.