Tried a couple of things to see if the bug gets solved:
- Re-installed the game. No dice.
- Tried walking back all the way up the staircase in the basement. Ashley makes a remark that the door out of the basement is now locked and calls for Chris. Chris says something like "What!" and his voice is as if he is standing near Ashley but his character model is still stuck at the exact same spot down in the basement corridor!
This is the spot that Chris is stuck at:
At this point I feel the game has screwed me over.