Contraint object to head working differently in FBT/3-point

Hi guys. Having an issue not many people could answer me about. What I’m trying to do is have an object follow the POV perfectly, very close to the camera. I was able to do this by messing with NearClip and constraining it to the head. Worked almost flawlessly in 3-point tracking.
But when I loaded into FBT, the constrained object drifts up and down away from the camera! It’s also skewed to the left from center (The object is perfectly centered). No matter how I calibrate it causes these issues.
Does anyone know if it’s possible to constrain an object to the viewpoint rather than the head bone? Or of any other way to fix this issue? Any information is greatly appreciated!