Steam: Adept Dredge achievement not activating when it should

Step 1: Play the game as dredge with only his 3 perks.

Step 2: Achieve a "Merciless Killer" rank with a double pip.

Step 3: The Steam Achievement "Adept Dredge" does not activate.

This happened to me on the map The Shattered Square. I have attached a video (as a gif) of the endgame screen clearly showing that I achieved the double pip "Merciless Killer" requirement as well as the perks I used (it did also say "Merciless Killer" at the end of the match, but I did not record this as I didn't notice the achievement hadn't applied in time). Also attached are a screenshots of the current state of my Steam achievements and the Steam summary of my last play session's achievements, as well as the logs from the game. I quit the game after this to preserve the logs and see if the achievement would activate upon exiting, so if there's multiple games in those logs it will be the last one.