Help!

I've just add a 3dtouch probe to the 3d printer . Probe works OK I've managed to configure it and calibrate offsets etc. BUT...
It is NOT probing the mesh correctly: (AUTO_BED_LEVELING_BILINEAR)
ATM - I hit bed level , it homes (to X-60, Y+120 , Z189 - Zero is centre of bed) , Zs down to probe but instead of moving to the expected Mesh I0J0 (which is X-59, Y125) it drops to the XY home ,probes 3 time across (X) but then moves the Y further forward into the stops.
If I move using a G42 I0 J0 (move to mesh 0,0) it moves to all the mesh points correctly as expected
It seems to be screwing up the initial mesh move ????
Ideas welcome..
Bill