Achievement: There's no I in Squad

Achievement: There's no I in Squad

Alright, it says that online you need 20 squad members spawn on you without you yourself dieing, well we got me, my brother, and my friend all in one squad, we all hid and me and my bro killed ourselves and my friend hasnt gotten the achievement, last time we tried, I died 23 times, my bro 21 so thats 44 spawns and he didnt get it, what do we need to do?

Also for trophies for example... The Mine trophy, do you have to stay alive on the last kill in order to get it? Because there were 2 times where I had 2 kills and placed a mine in front of it, but it either ran me over and I got the kill(s) or I was to close to it and the explosion got me, both times I didnt get the trophy... Is that normal? Do I have to stay alive?

NOTE: I do have that trophy, but it happens to me with other trophies as well, and yes we are on ranked, thats all I play