Ships not spotted though at VERY close distance..

[Vorfluter]

Hi all,

I recently made my way into an English harbour at night, yeah. But the anchored ships either did not appear at all an the map/target notepad or appeared only at very close distance when I almost ran into them.
Why don't the ships appear on the "system" while I'm able to see them very clearly through the periscope?
Is this a common problem, do you sink these ships without identifying them?

Thanks,

Vorfluter

P.S I'm running SH3 via SH3 Comander with the GWX 2.1 Mod