I have the same bug. I'll save this thread for when I find a solution or in case someone else finds one.
For now I'm avoiding Minthara as long as possible.
I'll also create a save game titled "Minthara before fight" so I can skip back before a fight if needed.
Update:
The Goblin seems only hostile to the Player Character. I can speak to her as one of my companions. Not ideal but a workaround.
