I unlocked Prismatic on my warlock a few days ago, and recently decided to delete and remake the character. After getting to the unlock room in the mission, I cannot interact with the pool of Prismatic energy to unlock the subclass. I have seen other reports of this on Reddit, where people have been saying they cannot reacquire the subclass on a new character that had it previously, or on characters of accounts that have more than one of the same class (an account with two hunters can only unlock it on one hunter, for example.) Just wanted to make this known on the forums so it can be looked into.