A small update has just been released as version 1.15.83.
This update fixes an issue where Chapter 5 could start incorrectly, preventing players from progressing.
A big thank you to G[u]T (https://steamcommunity.com/app/4568640/discussions/0/582805931178550550/) who reported the issue and helped me track it down so quickly. Your help is greatly appreciated.
Please make sure your game is updated to the latest version before continuing your adventure.