Recently, we discovered that High Contrast Mode has this issue on some of the backgrounds. The team is working on fixing this issue. In the meantime, to see the hints on the puzzle, turn off the contrast mode, and they will reveal themselves.

- Please go to the in-game settings (the gear icon on the bottom right of the home screen) > accessibility, make sure High Contrast is set to OFF, and recheck the puzzle.

I apologize for this inconvenience, and the fix should be released soon.

If you have any further questions or concerns, feel free to let me know. I'm here to help.