The problem with the achievement (Metro Exodus)

I sabavala achievement Saboteur tell me what to do all the achievements fulfilled one here that's unfinished, if that counter is stuck on the number 44 of 50. All I tried creating a new game when killing not noticed, when seen on different location when the enemies were also a melee weapon [on Yamantau] nothing helps tell me what to do please!!!

Game name:license no DLC [have not yet bought the DLC]

Anyone help thanks in advance