j'ai trouver sa sur des forums sur steam.
Hey! I had the same issue with my char. Another possible solution for the problem is the following one:
If you run the game on a higher speed ( fast, very fast) the bug is likely to come up.
If you find yourself having trouble getting the eye, go to settings, set game speed to normal, restart the game, finish the boss fight as usual and click on the altar. Should work out fine!