BACKGROUND
The unscheduled tasks backlog appears in three planning surfaces: the Calendar view sidebar, the Timeline right bar, and the Workload sidebar. It is effectively the same panel, but today it behaves as a dumb flat list in all three.
PAIN
Planners with real backlogs cannot work out of it. There are no fields on the rows, no independent filtering, no sort, no grouping, and nothing is remembered between sessions. "It is overwhelming and unproductive to see every single unsorted task I have ever made in that list."
WORKAROUND
People leave the planner, go to a List view to find the task they want, then come back and scroll for it. Or they change the view filters, which also changes what they see on the calendar/grid itself.
REQUEST
  1. Show fields on backlog rows, including Time Estimate.
  2. Sort by any field.
  3. Filter the backlog independently of the view's own filters.
  4. Richer filters, including hiding closed tasks in the backlog while keeping them on the grid.
  5. Save filter + sort combos as presets.
  6. Group with collapsible headers.
  7. Location picker up to Space level, not just List.
  8. Nest subtasks under their parent.
  9. Indicate tasks that are already scheduled.
This is one panel used in three places, so it should behave the same in all three.