I am very aggravated with this too. I went back on one toon since I have 6 now all stuck on the same bug and restart the previous chapter. made all different choices, now it is stuck before I even get to the talk to Theron part... They need to just allow us to auto-complete this or skip if they cant find the solution yet.

I noticed something here, not knowing if this helps investigate the issue, but if you look at your companion list before you try to start the chapter. Look at Theron. He is not available and it already says he has left alliance and you have a bounty on him, he is mad how you treated Koth.. So it seems the somehow progressed the story too far in advance so you cant talk to him if he is already gone.