One with the Shadows achievement not working!?

“Do not lose any units before destroying the Void Catalyst during the “Evil Awoken” mission on Normal difficulty.”
I’m sorta pissed right now cause I just did that on Brutal and got no achievement (and at least usually you still get theses “on normal” achievements if you complete them on higher difficulty). I had 12 Stalkers and 4 High Templars + Zeratul when I got to the Void Catalyst which is the max you can get to my knowledge. Weird sh*t is that when I completed the mission it said I had lost 17 units (Lost everything expect Zeratul on the way out, but that’s still only 16).
Is there a bug here or what? Is there something I’m missing?

Edit: Nevermind, you can apparently get 13 Stalkers. Can’t believe I lost one without even noticing, but I guess it’s the most likely answer. Oh well.

On the plus side, you get the achievement on normal if you crave it like I did.

Happens mate. Good luck next time.