Rock and Coil Hit Back Achievement not counting

Hey all,
So I’ve been attempting to knock out each of the achievements for MCC to get that glorious 100% on Steam and ran into a small issue with the achievement above. I played a couple rounds of 2A Multiplayer matchmaking and got a couple environmentalist kills while playing slayer and in each round got an environmentalist kill due to a couple fusion coils in each one. I know this is one of the tougher achievements to get so I was pretty excited, but when I checked the achievement list it showed no progress completion towards that 100 kills. So to brief:
Yes:
It was 2A Multiplayer matchmaking (not local/custom, yes Anniversary),
The Environmentalist badge popped up in each round stating it was an Environmentalist kill (I had no idea what the medal looked like before),
I fully completed each round and had no connection issues whatsoever.
Both times it was on Lockout Anniversary.
No:
The medals do not show up on my Career page as having ever earned them.

I have even gone through and re-watched and recorded the rounds to make sure I’m not crazy. One round was on competitive 2A Hardcore, the other was social Escalation Slayer. I could understand maybe if it didn’t count during Escalation because the game mode dictates “they don’t get official points for non-gun kills”, but I would at least hope it counts towards the achievement since it’s so hard to get already. Any insight or help would be greatly appreciated!

I’m also on Steam and working on my achievements and no achievements as of last night EST around 8pm have been popping for campaign or multiplayer. I was attempting to do the same as you and no kills are counting as well for the achieves I am doing in Halo 4.

same here in halo 3 campaign: no achievements popping (I found 1 skull and 1 terminal)