Talked with Jamien over in #⛏│game-discussion and figured out that in my game I have the dialogue immediately before the one where the chest code is provided, and I have the one after, but not the one in the middle with the code. Basically I know I have to go to Chapman's room, but not the code for the chest.
The only unusual thing that happened is I had to quit the game right after stanley was plugged into the AI containment and then disappeared. I saved and quit during that dialogue.
I don't remember rebuilding the antenna either. I did so after I found out that's the trigger and nothing happened.