Well, as I said: for me the quest did progress once I picked up tenebrium ore.
There are actually 2 places you can get ore to finish this quest:
1. in the Troll King's cave (as the quest would suggest)
2. in the Luculla forest mines, there is a tenebrium deposit you can mine.
You also find tenebrium ore on the Death Knights an the end of the mines but I'm not sure if they progress the quest and if you can finish it with those. Why do I say this? Because after picking them up and sending them to my homestead I now have 2 stacks of tenebrium ore, so they might be recognised as different.
Glad you could finish the quest though!
