Looks like it could be a PMC issue to me.......
The only difference between rotors stopped/low rpm and 100%Nr is the dynamic effect of the main rotor itself - throwing on pitch.
What is the Pitching Moment Compensation arrangement on a 412?
On a 47 it's done by the PMC weights, on a 206 it's a combination of built-in twist in the TT Straps and irreversibles in the servos.