Greetings, everyone!
Version 1.2.2 was uploaded and set to live earlier today to address a critical bug that was found in version 1.2.1 just before.
If you've had issues completing the first puzzle in the 3 Doors section of chapter 4, this could be the reason why.
Please check that your game now shows release build 1.2.2 at the upper right corner of the main menu.
I sincerely apologize for this, especially to those who were affected by this bug. Please do let me know if you run into any other issues.
Thank you!