All loops are not created equal. If you're having trouble with your loop constantly twisting to the side, the loop probably goes into the knots from the same side of the string.

Most pro-shop technicians know to tie on the loop so the loop material goes into the knots from opposing sides of the bow string, which keeps the loop centered and prevents twisting.

If your loop is constantly turning to one side, ask your technician to make sure it is tied to prevent twist.