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I completed the Fly Agaric mystery a while ago, and while going for 100% completion of Ledecestrescire i noticed that it hadn't marked the mystery as completed with the X as it had with all the other mysteries.
I went back to the location of the mystery and noticed that the Fly Agaric had indeed been eaten, so i had no way to restart the puzzle.
Attached vid shows the map without the X, the mystery bar with 1 missing element and the Fly Agaric with the already eaten model.
game version is 1.5.3.