I've created a plan with a bunch of existing tasks. Most of the tasks were not assigned to releases when I created the plan. It would take ~18 months to complete all the existing work. I'm most concerned with sorting out our priorities for the next three months. It's frustrating that the only way to view the next three months on the timeline has the side-effect of hiding from the scope view those epics which Portfolio says I won't be touching in those three months. It makes it very hard to adjust the releases and dependencies for issues so that the plan tells my team what to work on first.