"that just happen" achievement bugged?

so i have all of the achievements except this one, i have attempted this four times in coop on heroic, WITHOUT reverting back to checkpoint and i still haven’t got this one, I’m a really really stick off…does your partner and yourself need to survive?
or only yourself because i have only done it with just myself surviving

I’m pretty sure that only you have to survive.

Hmm i guess that means its bugged, how do I report this?

It happened to me too.

Nope, there’s no cheesing this one. No easy way out. In Co-op, if one of you dies, nobody gets it.

Im guessing you used a guest?