For some reason, Arma does not render all particles, even at close range. Once you look away from the particles and back again, the particles reappear, but disappear about a second later. This problem is very noticable on large particles, but happens on smaller ones too.
Some videos demonstrating the problem:
https://my.mixtape.moe/flftdv.webm
https://my.mixtape.moe/wwdjmp.webm
This problem appeared with the 1.62 update as far as I can tell.