PX4 where is initial local position?

#1

I use offboard mode for drone positioning at (0,0,3). My mavlink code command is (0,0,3) forever, but drone fly for (0,-6,3).

after flight, in flight log, initial local position(arming position) was (0,6,0).

why arming position was not (0,0,0)??

I use rtk gps for position sensor…