Phoenix Cradle does not seem to double the length of Sol Invictus. I noticed this issue before Destiny 2's King's Fall debut, and its been on again off again ever since. Like it will rarely work, but sometimes in when testing it in patrol, it spontaneously does. I have attached a link of a clip I recorded on my Xbox Series S, though I was originally playing on PC through Steam when I first had this issue in early Season of Plunder