Have you tried a different controller?
I have this issue when I play with my gf's controller, I dont know if its because I have a firmer grip that it causes that, but she doesnt have that issue while playing with the same controller. Sometimes I press L3 to hold breath & it releases ADS. or I press shoot & it knifes of throws a flash.
I just try to use my own controller which i guess is use to my grip.