Oh, no I believe that dialogue appears once all the clues there have been gathered. The bookshelf one is kinda useless. The dialogue you mentiomed just now was Victor coming in.
Viewing post in Detective Shade: The Turnabout Case jam comments
Your suppose to present clues to him and you need to get the info from Lucas to start suspecting and interrogate victor. At the end of the dialogue sequence, if you haven't fulfilled any of those, an inner monologue would give a hint on what you're suppose to do to proceed. If its the dialogue your softlocked at, try pressing enter. The bookshelf isn't meant to be interacted once you get all the clues.