Someone reported a similar situation for Jahan.
In the alpha there was a possible bug with Madora after speaking to a certain NPC at the end of the Black Cove, which could result in Not being able to speak to her, or sometimes other NPCs. In that case, walking out of Cyseal through the north or north east gate and returning could fix the problem.
Another person reported that they could still talk to some animals, and successful conversation fixed more dialogues for them, until they could talk to everyone again.
Maybe email supportdos@larian.com, with a description of the problem and the report.zip file generated by the
D:OS support tool (for the PC version). The report will contain your saves, which may help Larian fix the problem (if file size is an issue, you can delete older saves, leaving at least one before and after this happened).