Wandering True Position Tolerance

[[Pe...]]

Hello,

I am trying to get true position on a number of holes.  These holes are fully constrained  with a 3 plane -  |A|B|C| DRF.  These are MMC positions.    

The true position values are anywhere between .013 and .045" off of nominal.

When I take a Cartesian dimensions of the holes, they are within .0005" of nominal location of A and B datums.    Why would my true position be out when everything else is right on.

I did have the same issue as in this thread:  

Thanks,

Pete