I'm having the same exact problem. Shoot control panel and the door does NOT open nor does a heavy appear.
I've tried this multiple times solo and with friends and the door never opens.
Please fix this already!
I accept the help call, talk to the player ask him if i can go to the sewer/tunnel. We go there, and shot the box. The door Open, the big guy appear when we leave the room. Drop the Key and we completed the task.