Understorm Gold Mine door won't open

Hi

I'm doing "Looking for evidence in Understorm mine" quest and when I reach the door that leads to "Search for evidence" point in the map, I used the Understorm Gold Mine Key and it displays the next message:

"Your key (Understorm Gold Mine Key) broke during use"

Tried with another one and it just says: "Already unlocked"

And door won't open.

 

@Moonrider, this may be a a bug but may be a matter of you being TOO accurate in your clicking. one must click the lock to unlock the door, but click elsewhere on the door (not on the lock) to operate it once it's unlocked. getting a message that says "already unlocked" sounds like you're clicking the lock again. ...or it's actually bugged.

 

The problem is that it's says the door is still locked:

 

Well, looks like going outside and back to the mine have solve the problem, now it opens