I've been noticing some weird behaviour with Vassals and Hidden Nationality.

For example I've had privateer attack my ships me and the message that's displayed actually tells me that the ship belonged to my vassal.
Yet when a animal with hidden nationality unit that I know for certain belongs to a vassal attacks my units I'm not told who it belonged to.

bug (or just poor design) from 3.13 BtS. If I'm not wrong, Bhruic patch corrects this kind of behavior from the Vassals (especially in regards of BtS espionage).