The caustic cloud skill in the siren’s red skill tree prevents progress in challenges of critical hits and kills or optional objectives such as critical kills in fink’s slaughterhouse.
not a bug, CK is just OP it is stealing your crits. Try respecing out of it if you are farming challenges.
Also, you will find the MMORPGFPS side mission in Tina DLC, the Headshot one very frustrating as well.
This isn’t a bug, nor is it a PS4 specific issue. The skill creates an area of effect damage over time effect, it does exactly what it’s designed to do and therefore is not a bug.
If you’re desperate to complete challenges with her, simply respec and don’t choose Cloud Kill, after you’re done you can respec again and put it back on.
i did not recognize you on your new avatar, lol. Back in Borderlands?
Basically going through more before 3 comes out