Dang, sorry you got this one it does seem to be a bug. Any info you can give about your save - did you play from the included option to start at new content or from your own save, do you have any other quests still available, what was the last quest(s) you completed before this?
This seems to be a very rare bug as you're the first to encounter it that I've seen, any help in fixing it is appreciated!
Potentially, it should just be tied to interacting with the door or being inside the apartment after completing the fancy dinner date but there's obviously something interacting and breaking it.
We will look into it and see what's going on, in the interim you have any save files close to this where you could reload and see if trying this quest earlier fixes it?
If not, starting a new game and choosing to start from latest content will get you to this part of Leslie's quest
