San d'Oria Tutorial Quest can't Advance

Hello, I'm trying to complete the San d'oria miniquest, I'm very new in the game.
The problem is when Alaune sent me to La Theine to kill a monster. I killed a rock eater. Returned to Alaune, and nothing happened, she still need to go to La Theine and kill a monster.

I searched in an another posts and found the same bug, but it solved. The problem is in that post they can´t explain how it solved, only say: "I have no idea what fixed the issue."

Please help me with this issue, I'm new in this game, but I'm entering in a wonderful world, I'm feeling optimistic.

Thanks.