Is it the "harder enemy escorts" mod you are using?
If it is... Thats the reason.
This mod is not working as it should - no offence.
The problem is that when installing this mod the data/cfg/sim.cfg is changed.
If you open it in notepad you will see, after the [hydrophone] bracket, a line called sensivity.
When you installed this and replaced the sim.cfg this line was changed from the value 0.03 to 0.01.
It should be the other way around. Open the file yourself with notepad and change it to a higher value. Higher value will make the destroyers hydrophones more effective. Lower value will make the destroyers deaf.
It took a lot of testing and reading for me to understand that it should be the other way around. If you don't have any luck - PM me and I'll send you my sim.cfg file.
With this you will surely have DD's with working "ears"
