[propbeanie]

The game can only do one "sensor" at a time, so you might start with a "Sonar target, blah blah blah", and you'll see the sonar line(s) pointing at your "target(s)". If you have a radar detector and then receive a "Radar signals detected!" message, you will now see the radar signal line pointing at your "target", and the sonar lines go away. If you then make contact on radar, the "radar signals detected" line will go away, and you have your radar "blip" to go by. Then comes visual, and as soon as visual contact is made, all other information is redundant and goes away. This applies to ships and planes as they come into visual range. So you might have a mix of various lines and icons representing potential "targets", but none of them will have more than one type of sensor detection associated with them. The "visual contact" you describe can happen even when you have your periscope down under certain circumstances, but if you drop a pinch in depth, you will usually go back to the default sonar contact lines. So if you are seeing icons on the map, check your periscope, and if necessary, go to 20m or similar, something below PD. Give the game a few minutes to "lose" that visual and give you the sonar back...