WotLK Brother against brother quest bug

[biohazard9193]

Hello,
yesterday my guild friends and I formed a group to do the 2 quest:
brother against brother "first boss"
terokk's legacy "last boss"
However, when we kill the first boss we encounter a bug, we can not release the prisoner "lakka" required for the quest, which should be able to be released soon after killing the boss, killed the last boss (we completed the quest terokk's legacy) and came back where the first boss was and again we tried to release "lakka", but without success.
I really wish I could complete this quest to get the neck for tank
print of the quest:

Spoiler: Show

https://prnt.sc/kfqpfh
https://prnt.sc/kfqoen

thanks for listening,
Att. DKingSlayer

[Anyone0]

Bugs have to be reported on bug tracker. This one is already there:
https://www.warmane.com/bugtracker/report/47964