If you loop measures 1 through 4, the clock would read these grid points correctly on the first pass. After the first loop, the clock no longer recognizes being positioned in the measure 1, and instead assumes the position of measure 5. Therefore the clock reads:

[ 1 2 3 4 ] > [ 5 2 3 4 ] > [ 5 2 3 4 ] > etc

While looping your DAW, the clock acknowledges the loop END point to trigger the Grid Change instead of the START point.

Is there a way to get the clock to trigger on the loop START point? Or is there some other way to double check the playback position?