Help！That must be a huge BUG!

I can't get to Act 6! Although all the quests of Act5 have been completed, the boss at the end of the level has been killed twice, but it still can't end this Act5, and the plot can't be triggered. What to do!?
Two tasks are displayed all the time, but they are repeated and still cannot be finished.However, it has already been shown "quest complete" in the quest list.“Acent to power,the trail of corruption” This is a bug, please help me as soon as possible