The contacts in the map are only visual. So they appear when surfaced or at periscope depth and with some scope up - this simulates your XO or crewman observing through the scope. All visual. When underwater without scope up or destroyed you have only sonar contacts or radar - if at radar depth. But this contacts are lines indicating direction of the contacts. In SH4 visual contacts prevail over all other contacts. So in the map the visual
contacts not ever are in the direction of the sonar lines.
Then you want a full contacts deployment when submerged but I don't know any mod or way for that.
Best regards.
Fitzcarraldo