I can also confirm, that after you are clearing all maps, the achievement is given.
Hereby also my statistic about the kills pro level
Operation Daybreak 60
Operation Falchion 59
Operation Nightfall 117
Operation Cleaver 152
Operation Rapture 124
Operation Blindfold 170
Operation Magpie 147
Operation Trident 182
Operation Aries 213
Operation Harbinger 205
Operation Reunite 165
Operation Wave Breaker 194
Operation Guardian 256
Operation Reckoning 229
Overall 2273 - but the achievement was given
有一个老外的帖子,他说数字差点但是给了成就