I got the same bug, and it was my first task, so it just seemed like it was either deliberate or the whole game didn't work :(. Without the comments I wouldn't have known it was worth reloading and restarting
I also wish there was omething that froze input while people were talking, rather than making them into concrete blocks that magically stop being concrete when they are done - feels weird and frustrating not to be able to walk past them, then they look identically but now you CAN walk past them.