You have probably been showing a 'sideways' profile to the sonar/asdic cone. I have personally experienced the same phenomena on a great many occasions.
Nobody ever said the AI in GWX3.0 was easy, it was finely tuned to be both challenging and immersive and that is a hard act for anyone to perform considering the number of super mod users and their diverse set of beliefs and requirements.
On a humerous note....if something was 'buggering' me for a long time I would be steering well clear of it
