I completed The Final Shape campaign on my Hunter and unlocked all Prismatic fragments account-wide. I have unlocked all prismatic on my Titan as well. On my Warlock, Arc, Solar, and Strand are fully unlocked (including Strand grenades and fragments). I have completed Transmigration, Temptation, and the third campaign mission. Prismatic is selectable, but Ghost in the Pale Heart never offers the quests Lost in the Light or Found in the Dark. I have entered Pale Heart patrol, completed Overthrow activities, replayed missions on Normal and Legendary, and checked the Quest Archive. This appears to be a character progression flag issue preventing Prismatic aspect quests from being granted.