Legacy of the vaal stone altar missing large soul core from construct

After acquiring the large soul core from vaal constrct inside machinarium , i went ahead and did trial of sekhema. Something inside my brain glitched, and i have dropped large soul core i had and it dissapeared completely ( not even appeared on the ground after i have dropped it in the trial ) . I cant place soul core on the altar in infested barrens, and consruct doesnt drop me one. What am i supposed to do ? Playing on SSF, cant ask anyone to help me either since transfers are broken.

At this point my character is softlocked, and im wondering whether there's a fix