Blackstar quest skiping the boss fight

Bug Name:

Blackstar quest skiping the boss fight​

Bug Description:

Quest Name:
[Blackstar Weapon] To the Altar of the Fallen God
[Combat] The Incarnation of Corruption at Star's End

Step that is bugged:
The boss fight

What is bugged with that step
You can skip the boss fight

How to reproduce the issue
During "[Blackstar Weapon] To the Altar of the Fallen God" you get this quest "[Combat] The Incarnation of Corruption at Star's End" and if you cancel this quest and then change character and then go back to your original character it removes the need to fight the boss it just says that you defeated it and you can go forward with the quest line. I tested(tried to get better gear because i wasn't able to fight the boss) twice once by chosing the quest that lets me fight the boss directly and once on another character by chosing the other way and going to tarif and killing the 1000 helms, it works the same on either of the 2 ways.​

How to reproduce/proof:

I don't really have any proof but it should be pretty easy to reproduce with what i wrote under "How to reproduce the issue."​