That's a bit tricky to diagnose. Number one, there is only one opportunity for the Hart scene to trigger per day. If you go into the bathroom and it doesn't happen, it's not happening that day. So if you try and move back and forwards between the hallway and the bathroom it is never going to trigger. You need to try again on subsequent days.
That said, if you have had a reloaded to a save made before the Hart scene was triggered there is nothing that should prevent you re-experiencing. If it really is impossible for you to see the Hart scene the only explanation I have is that your save actually has recorded the scene as done. In that case the next scene with Hart will be randomly encountered in the Hallway (again, only one chance per day). So you should see one or the other if you go from Hallway to bathroom eventually. I can't think of any other reasons for your predicament.