I have an Elite7 HDI and I change the chart to north up on the bow unit so that when I'm fishing structure and not moving I have a better idea of structure orientation as I slowly work around the structure.

When it is on north up vs heading up, the chart does not move at all. Shouldn't north up use some internal compass and keep the map point to the north as the boat moves? Mine just keeps north on the top of the chart and never moves.