OK I just ran it again and it did not bug.
The only difference I did is that I did not keep clicking on the sickened Quaqaan at the end.
First time I ran it, I kept clicking on him during the dialog.
Second time I just clicked on him and waited for him to give his speech and then transform.
Hope that helps you guys.
This works for me today, just make sure ONLY ONE CLICK on sickened Quaqaan .
Thanks Nadeen.6371!