full arsenal won’t unlock

Idk if ”final duty” i need to get the ”full arsenal” trophy. I’m really pissed that I can’t get the platinum when I have all of the other trophy’s. Except the “full arsenal” trophy

i have tried 3 times or more trying to get the full arsenal trophy but it won’t work

i have all collectibles I idk if I need to weapon assignments or the “final duty” assignment to get the platinum trophy