Theres a difference between “Have Placed a mine” and “Started placing a mine” but not in Anets eyes. This happened twice where I’m going through the mission, and click F to grab my turret and my engineer starts to ‘place a mine’ instead because they’re in the vicinity. I immediately stop him, but I lose the buff for doing the achievement. The mine was not placed, even after this I can still place a mine in that corpse because it was interrupted. So case and point, the mine was not placed as the achievement specifies, but I still lost credit for it. Fix the way events like this are handled in the game engine.