Environmental kills do not register on the scoreboard across FFA maps. Tried using Pharah Concussion Rockets to drop people in water on Chateau, used Orisa’s grav to drop people down the hole on Petra, knocked a guy off the side on Dorado with Wrecking Ball, etc etc
They don’t give kill credit, any of them. They’ll show up in the kill feed, but won’t add to your kill total.
While Hammond should technically register, there is indeed a bug with Pharah, Orisa and with Rein’s charge, if he charges the target out of the map instead of into a wall. My theory is that it happens to knockback effects that do not deal damage on the initial hit, such as Concussive Blast and Halt. Though it is most obvious in FFA is definitely not exclusive to it though, but a problem in every mode, ever since the most recent patch.