When was last patch? This game was started yesterday, and continued today.
This was an exploration age village. I actually never saw them; they appeared like this in distant lands. I am pretty sure I sailed by here and they weren't there. Then I sailed back later and they were there. As if they spawned incorrectly. Are IPs supposed to spawn mid-age? Another (normal) one spawned that wasn't in my game at the beginning of the age. Kind of like how barbarians spawn in previous civs.
Update: I now have an invisible scout, myself. This unit was visible on the previous turn, but he went through storm. I have not loaded any savefiles between those 2 turns.