for what i could see (i tried recording a video on Geforce shadowplay but it was just black), i made myself die to the first enemy after the second save point, the puddle dissapears before going back to the game, then i returned there there was nothing, killed that first enemy that killed me, and keep going forward, and i still could not recover.
i will try to get a video with obs to explain better, i didn't see anybody having this problem, and i think i am not understranding something.