Does this only happen in the sim? Or also without the sim on? And also did you do the balance spring setup to compensate for the weight of the grip and extension?
In your video posted on the diy section I noticed that your balance spring setting is disabled. You want to disable all effects and enable the balance spring effect. Then modify the force values to where you can move the stick in any position and it will stay in that position.
The balance spring has 4 values. Basically it applies a force opposite to where it's put away from the center. You don't need much force on it. Just little by little adjust until your stick doesn't spring back
It has a cyclic spring gain which I have checked on at 100%. Currently I'm moving the stick with the spring on and force trim and it appears to stay in place without running the sim