I’m split your post away from the one you replied to as it does not have anything to do with the original post. You will get better answers this way as well.
Was the 898 unit the only sonar unit that was being used on your boat at the time?
How do you have the 898 unit connected to power, is this to the boat’s wiring and fuse panel or is this by its own set of wires run directly to the battery?
Depending on the map data that was there and the zoom level you were using was as well as the Background color menu setting in use will determine what color the unit will display for that area.