fotm zerker and fire elementalist bug
There are many instances of this bug, from my speculation it happens when your rapidly pressing the 2 key in expectation of going down (or spamming skills in general).
Ethereal Guardians [EG]
Sea of Sorrows
Sea of Sorrows
IMO none of the skills pressed before go down should activate downed skill, and vice versa. Playing as elementalist i often enter in vapor form because i was spamming #2 skill. And as engineer, i get knocked down because of the #4 rifle skill, right before i spam bandage while downed.