missing soul core in trial of chaos

I ran an Inscribed Ultimatum area level 79 10 trials. I completed 2 rooms. got to the 3rd room which was a put the soul core in the alter. I went through all the areas and there were no soul cores to carry to the alters to put them in.

i currently ran into this problem, i have an idea where the soul core is but it requires me to use a switch to raise a bridge with noclear way to access it.