It's been added in the previous update. But only for MM1 so far. I actually tend to use a plugin to make it so that target flashing doesnt appear so I didnt think about it :P
Yeah, I got all three packs and noticed that one set had outlines. I'm surprised you hide the flashing targets, because even an enemy's death animation alters the pixels so it fades out with colouration. I guess you could just make it fade out with increasing transparency instead? Thanks for awesome monster packs, either way!