I used a tied in nock between the nock and the bottom knot of the loop. When I checked my form in the mirror one day, using just the loop, I saw that my release had pulled the loop up at an angle, so the release was actually above the arrow. Putting in the nock point above the bottom knot changed the angle on the bottom leg of the loop and brought the release down so it was directly behind the arrow.

Once I did that, some of my tuning issues went away. I'd had a bit of a problem with vertical stringing of my groups until I added the nock point.