Once you unlock it via the quest, press the Y button to pull up your legacy window. In the menu under Character Perks, you can pay cartel coins to unlock him via any additional character on either side. That's the best way to unlock him
If you wish to do the quest, go to your collections here and you can click the house Icon to unlock the item. Make sure your doing this on a character that you haven't bought it for yet.
"Once you unlock it via the quest, press the Y button to pull up your legacy window. In the menu under Character Perks, you can pay cartel coins to unlock him via any additional character on either side. That's the best way to unlock him"
That is only the best way if you only have very few characters as you'll have to pay for every single character. The other method is a one time payment to unlock on all current and future characters on all servers.
I provided both methods of how to unlock him more than once. If the second option that I provided in the screen shot doesn't work, sometimes logging out of the game then back in fixes it. If not then can try to submit an in game ticket if the icon in the screen shot isn't lit up to select
Thanks for providing a rundown of how Treek can be unlocked, but the problem isn't that I don't know how to unlock Treek for new characters.
The problem is that despite unlocking Treek on one character, through the Legacy vendor, the Mercenary Contract hasn't been unlocked in my Collection. I can't pay to claim it on additional characters because the Collection doesn't recognize that it should be unlocked. This, despite the official SWTOR blog I linked in the first post, which explicitly states that both the Cartel Market or Legacy vendor contract should unlock the Collection item.
I have tried logging out and logging back in, switching to various characters, waiting 24 hours, etc. I was hoping that EA/Bioware would be able to suggest some other workaround or solution.
