I think both this thread and
Game becomes unresponsive - Gnarled Door are talking about the exact same issue you're describing, where the game has to transition a dialogue scene into another location for the scene through a
black fade in transition, but the black fade in transition does not progress into the next scene. So you still have your UI and buttons and can hear everything, but cannot do anything.
I also experienced this issue myself, however only once and never am able to get it cooked into my save file, as quitting the game and reloading fixes it for me.