This is still happening...responding here as well to make sure that this issue is seen and acknowledged.
Torian is still completely missing for me after 4.0.1 as well.
Yes same here did Taris on patch day 4.0 and got Torian logged had him summoned so i continued missions and after i logged in day after he was gone. And is still missing have had ticket up for about a week now no response and I'am lvl 60 and ready to do KoTFE now.
Appears a few things didn't quite go to plan with last nights patch....
Don't stress its Tuesday in your part of the World and Wednesday here... so using my pretty nifty skills to tell you how tomorrows going to go, I can say for sure and a 100% clarity Wednesday will end in a y.
I just got Torian on my bounty hunter, and he was in my companions list briefly. He is no longer there after I finished the Taris mission completely.
