Are you by any chance always going downstairs at the end of date 3? That leads to a safe or bad end. To continue the story, you're supposed to ignore the interphone.
I already tried not to go down and followed the only tutorial I found to get there but I always get the sign that it is not finished (and yes, I started a new game as you said in other comments but nothing)
Unfortunately I don't have the opportunity to reinstall it in like 5 days, I'm on vacation and I don't have good wifi, when I manage to do it I'll tell you :)
I recently tried it (like three times) but it didn't work. I have no problem watching some gameplay (if I find it) or waiting for another update but I really don't know how to help so that another person doesn't have to go through the same thing as me ;(
