Anyone else have this achievement problem?

I should have gotten the Emergency Room achievement a couple of games ago on Reflection, when in the third round, I infected three of the survivors. Much to my annoyance, I didn’t get it for some reason. I was in matchmaking, in a regular infection game, and got the three infections in a single round. Has anyone else had this problem?

Unlike the Noble and original Defiant achievements, the new Anniversary achievements must be done on an Anniversary map. Similarly, the new Defiant achievements must be done on a Defiant map. I do not know why 343i made this unfortunate choice.

haha yeah, its impossible to get, coz you dont get those maps for infection XD