The SI is showing up and down movement of the jig. The black area on the left and right of center-line both display the area directly below the Xducer. That black area is the depth of the water below the Xducer thus the jig will show the up/down movement.

The jig is on the left side of the Xducer according to the screen setting displayed.

That is how I understand it after a Lowrance seminar.