I used to suffer from a type of TP where I couldn't get to a solid anchor and it was caused because I was being triggered by the sight picture.
Thankfully after watching every dvd, read books and post, tried everything...no luck. Until a FITA shooter with super solid credentials gave me a drill. Get close, 5 yards, and when you draw your bow, watch the arrow at your bow/arrow rest until you reach anchor. Then shift your focus to the target, you will have to adjust and move to the target. It will feel weird at first, 50 shots later and you will get the hang of it.
After awhile you'll notice that getting to anchor is no longer a problem. Next you need to work on moving into your bullseye and executing the shot. I move into the bullseye, tell myself I'm "On" and then make sure I remain strong on follow through. Once you get the hang of it, move back a few yards till you get as far back as you want to go. Basically you are removing the trigger to fire at the sight picture. Along the way you build solid form, solid form muscle memory, and a fine taste of leather in your mouth. And most of all you begin to build a solid platform to explore other parts of your shot.
Short disclaimer, I'm not a Pro, not trying to sell anything, just trying to give back to those you want try something that might work for them.