I also figured out recently that I was gripping my bows a little low. I always shot curves with more pronounced grips. Now I shoot more D/R LB's with low or locator grips. Even my Firefly has less forced grip location than some of the bows I used to shoot. Shooting some bows this weekend at Kzoo really showed me the difference again. Bows like the BW standard curve grip, Tall Tines, and Shrew really forced my hand up tight to the shelf. I brought that home and started to really force my hand up higher in the grips of my bows. What a difference!! That with the more natural pull angle, not trying to force a low elbow low, really makes a difference. I shot quite a bit yesterday and today. There is no doubt I have figured it out. My arrows fly great now, and they are right on for tune. I made a little tweak on brace height yesterday on one bow and did the same today on the second. They both really dialed in.
The slight low grip and forced low pull are why the grip and compensation with the sting fingers yielded positive results on early attempt to solve this problem. Most likely I let my grip slip down a little with the bow changes. Then in working on my form changes I made a mistake of forcing string arm vertical alignment. The two together really caused a lot of problems That nock height and arrow spine couldn't solve within reasonable adjustment range.