Artillery Barrage achievement bug

Recently I have tried to get this achievement to get the Pirate Barrel for my GL40, but not a single one kill I made was counted in the progression bar, and I have killed over 50 in fact, so that cannot be only display bug, it must be bugged achievement. I'm also sure, that it was the needed +40 meters, because I had target marker to get a drill that was showing me distance to it, that was 45 meters from my vantage point. I've seen that some people on forums also have this issue, but I can't find bug report about it, so I'm making mine.