Tmeple of Chaos Soul Core Bug

I was traversing through the temple of chaos with a friend and got to a soul core room. I went and picked up the last soul core and was told by the game I didn't have it when I tried to place it in its altar. For some reason my friend was able to place to place it instead. The only real problem was the game still considered the soul core on my back. Meaning that I continued to periodically take damage. This persisted through multiple rooms until it finally ended our run.

Same thing happened to us. I picked it up and the game didn't allow me to put it down, but it was siphoning my energy shield and health the whole time. My friend could place it down without picking it up (it was still eating my ES and HP) and it was spawning monsters in a boss room. I had to exit to character screen to not die when my potion was empty, but couldn't unfortunately rejoin my friend in the last three rooms. Everything was fine earlier (we did about 20 runs until now without any problem).