@Syko_Symatic also bear in md that a G30 probe (which you are probably using to establish ZX=0 at the centre of the bed) probed wherever the head currently is, whereas G29 takes account of the probe offset. So the XY coordinates of the initial centre probe need to correspond with the XY coordinates of one of the G29 probe point minus the XY offsets of the probe hat you declared in your G31 command.