Streamer and community contributor flamu has noted and confirmed that the Situational Awareness skill isn’t working as it should. If you remember from the 5.5 patchnotes, there was a little bit in there, kind of buried away, that stated ships firing from concealment wouldn’t suffer the 20s detectability penalty if the penalty wouldn’t result in them getting spotted. Well, that seems to have messed things up, and now people with the SA skill (especially playing destroyers, of course) are suffering for it.
This is almost definitely a bug and not a hidden feature, and WG staff have said they’re looking into it, but that the issue hasn’t been verified. We’ll see how things go; the last major bug was fixed quick, and hopefully the same will be true for this.
Sources: https://www.reddit.com/r/WorldOfWarships/comments/4hfv4o/psa_situational_awareness_is_clearly_bugged_right/, http://forum.worldofwarships.eu/index.php?/topic/50464-someone-forgot-to-adjust-situational-awareness-in-055/page__st__60__pid__1002724#entry1002724