Some of our teams are using the PSI Feature Burnup as a work around. We would LOVE a similar but more flexible app that can show burn up for a Milestone with the preliminary and refined estimates from the connected portfolio items.
The PSI Feature Burnup pulls release-based data from your lowest level portfolio items (Features) and can be filtered by higher level PIs and/or Milestones. If you connect the Features directly to the Milestone (rather than letting them inherit from a parent PI) and include all of the Releases into which the Features are scheduled, you can get a burn-up chart that includes points plus Preliminary and Refined Feature Estimates.