After some more combat, I found out that it's by itself. It isn't the bosses' fault. The evasion mechanism is wack. It happens only in target lock.
Did input the sidestep evasion, and this happened with Warren doing the forward evasion. Same goes with the back evasion.
I noticed something weird.
I wouldn't record it in the video, since I couldn't prove my point there. Almost every time this boss spits its blue flame on me I try to evade it horizontaly, but instead Warren goes head-on towards the blue flame itself.
This happens only when both Warren and blue flame are at the same direction. If you guys need the video, I could record it next time I face it.
I hope you guys fix it, so that it will bring in more Dark Souls fans, like me, in this game.
I will find more bugs along the way and report them to you.