Potential bug with field of vision (not sure what to make of this...)

[Danny Pockets]

I posted this issue as part of a discussion forum post, but I think it was tl:dr and it was ignored. Now that I've gotten over that, I'm going to repost here it because it did feel buggy. I'll just quote from myself, because how do often do you get to quote yourself in life without sounding like a complete ass (don't answer that):

So I've got a soldier crouched behind a flower pot (you know the ones). This is just outside the chopper (on a terror mission map). He's not looking directly ahead, he's angled to the left (but not facing left). I send another soldier round from the back of the chopper to take cover beside him, but as she comes round the chopper she stops, because it turns out a Reaper is next to that first soldier, only one tile away. Scared the hell out of me! Where did that Reaper come from, and how did it sneak up on my soldier like that? This is right at the bottom corner of the map, so it didn't sneak up from behind, it had to cross the road to approach my soldier. And my soldier wasn't facing hard left, he was only angled left a little, so unless it turns out these guys have shocking peripheral vision, I don't understand how that damn beast crept up on me like that, and why it was only revealed when my lady soldier came around the chopper.

What I forgot to add there and which is actually the important part, was that once the Reaper was revealed I immediately moved away the soldier beside it. And when I moved him, that area went back to being blacked out (this was a night mission). So the Reaper was only revealed as the lady soldier came round the chopper to face it, but apparently she did not have sight to it because moving away the closer soldier blacked that area out. But that closer soldier also apparently didn't have line of sight because otherwise why was it only revealed as the second soldier came around.

So that seems like a bug to me unless I'm really missing something about how sight works.