I suspect the tanker mission is a stock mission, and not designed with SCX2 in mind. Therefore whoever is firing at those tankers might be to near them, in relation to their sensor (increased ) sensitivity. You can find more missions designed specifically for SCX2 on Bill Nicholls' (Subguru) site:
www.subguru.com
As for artic hide and see I am not sure what could cause you to be deaf. Is your towed array broken perhaps? Or is it hiding in one of your sensor's deaf-zones. If it is slow it is very quiet. But you may also have to adjust the intensity or gamma settings of your monitor/grahics card to enhance the display of the faintest narrowband signals. One of the missions on subguru's site had a screenshot of the narrowband in it which you can use as a test-image. Unfortunately I can't remember who made it or what it was named.
[EDIT] It's in here:
http://www.subguru.com/missions/SCHQ_TACMAN_PDF.zip