I have an Combat preview here of a sub with an assassin and Lieutenant on board attacks an outpost without specialists but it still shows the text: "
<PlayerA>'s Assassin killed <PlayerB>'s
<PlayerA>'s Lieutenant destroyed 5 drillers.
"
Note that the assassin doesn't have another specialist to kill, so it leaves that part of the text empty, but it's weird that it's there at all.

Maybe relevant: There are specialists of B (that's me in this case) in the outpost, but I've scheduled their exit, so they'll be gone at the time of combat. This schedule exit is also really close to arrival of A's Assassin.

thanks timo, i added it to our list.