When running Vow of the Disciple we had noticed on the Caretaker encounter that if you have a Weapon with an Incandescent roll shooting the Obelisk to give your offerings, it would scorch all symbols and reject your offering. Now I am not sure if this is a bug or not since you can cleanse the Offerings on the Obelisk with Osteo Striga. I will see about trying to get some sort of video of this.