Hartlepool AA Guns Side-mission broken?

[Mediocre]

After completing 2nd patrol mission (Tonnage War AN19-AN55) in North Sea, I got a side-mission to recon 2 AA guns in Hartlepool. Getting in was easy - had some distant hydrophone contacts but they left and never came back.

I timed my arrival for a night recon. I had the entire port in my visibility, but no success. I surface about 300 meters from the entrance of the port. Still nothing. I drive around all sides of the little peninsula. Still nothing. But the little green objective dot was inside the port itself, so I figure I'll go for it. I enter the port at periscope depth and still nothing.

But there was no moon that night, so I figure maybe it's just a visibility issue. I decide to try daytime and leave the port and wait.

I repeat much of the same process during full daylight, and still no success. I go for broke and decide to surface the boat... still nothing. So now I am surfaced inside the port of Hartlepool in broad daylight and I still can't see these AA guns and accomplish this side mission. Also - no enemy engagement, nor radio traffic.

The port has been dead for the 12 hours I've been here, so maybe the locals need business? Think I can get them to top me off with fuel, ale, and bangers before I head home? ;)

Has anyone accomplished this mission?

[SoulShock]

I went on this mission a couple of days ago. It's not enough to just be on or near the green dot with the sub. Take the UZO/periscope and look directly at the AA gun's in port. They should have an orange icon appear once 'discovered' by your crew.

[Para]

For the AA gun missions, get within clear visual range, put your UZO/periscope center hair at dock level, and just spin around. That'll be enough to tag those gun emplacement, unless obstructed by a building or ship.

[Mediocre]

Ok thanks. I'll keep that in mind for next time.

FYI - As soon as I started moving, I was spotted and they sent aircraft. Guess they were mad that I left without buying anything.