Check the ball links. The ball side, where the small screw goes thru the ball. Sometimes the little screw gets bent and moves around under a load. Also check the plastic portion of the link. Sometimes the threads on this plastic portion strip and can move under a load.

Additionally, I recently saw a pair of medium priced carbon fiber blades that were warped and showed the same symptoms. On track at a certain RPM, but out of track at a higher RPM.

I just read your post again, what do you mean of tracking on the ground? There is only one way of tracking, and that is on a hover (in the air). Please provide further information about your tracking technique.

Rafael