Issue Summary

The auto-schedule feature in Advanced Roadmaps doesn't respect the ranking of issues on a plan based on their story points in some certain scenarios and sets the Target End date much further in the future than expected.

Steps to Reproduce

1. Create the first Epic worth 45 story points.
   1. Assign unresolved stories to it.
      1. Story A - 8 story points.
      2. Story B - 5 story points.
      3. Story C - 3 story points.
      4. Story D - 3 story points.
2. Create the 2nd Epic worth 310 story points.
   1. Assign no stories to it.
3. Create the 3rd Epic worth no story points.
   1. Assign unresolved story.
      1. Story 1 - 100 story points
      2. Story 2 - 100 story points
      3. Story 3 - 100 story points
4. Create a Sprint A and assign only stories under the first Epic
   1. Set sprint start to today and end to 12/31/23
5. Create a Sprint B and assign only stories under the last Epic
   1. Set sprint start to 1/16/24 and end to 4/22/24
6. Assign the same team to each Epic and Story in the plan.
7. Try to auto-schedule the plan and confirm Target End is much further in the future for some Epics.
8. Re-rank an Epic to the top and confirm the issue still occurs.

Expected Results

Auto-schedule should correctly set the Target End date.

Actual Results

This screenshot shows that the Target End date is much further in the future:

Workaround

 The workaround below only applies to Jira 8.x, as it requires switching AR to the Legacy UI, and according to this Community Article the Legacy UI won't be available to switch back to in Jira Data Center 9.0 so this only applies to versions Jira 8.x: 

Support for Live Plans in Advanced Roadmaps will be removed from Data Center 9.0, which is expected to be released between May and June of 2022.
The Improved experience for Advanced Roadmaps will continue to be available.
This is an update to the same change we announced in January 2021 and have since made in Cloud in July of 2021.

The only workaround is to switch to the Live Plan legacy UI and use the Set target dates from calculated function then switch back to the new UI:

Users can switch to the Legacy UI by modifying their Plan using the configuration cog:

Next, open the Planning Interface page and toggle the "Disable improved interface" button: