Migrating workflows on existing projects can impact Agile reporting if statuses are changed

Summary

It appears Jira Software loses viability on an issue's change history when a previously existing status is removed ( changed ) from the project's workflow. This affects the historical reporting on the various agile charts for the affected project.

Steps to Reproduce

1. Configure a workflow with the following statuses
   1. Open -> In Progress -> Resolved -> Closed
2. Create a sprint, add an issue from the backlog, transition every step from Open until Closed, and complete the sprint
3. Create new workflow with the following statuses
   1. Open -> In Progress -> Status 9
4. Migrate workflow, map issues in Resolved and Closed to Status 9

Expected Results

Agile reports are unaffected by this change

Actual Results

Sprint report show issues moved from Resolved and Closed to Status 9 as being In Progress and Removed From Sprint. Cycle Time is also incorrectly calculated for these issues as well. See attached screenshots.

Issue history:

Sprint report:

Notice how the Sprint report shows issue 1 as Open instead of Status 9

Notes

Other Agile reports may be affected from this change.
While the original report comes from Jira 6.4 / Jira Agile 6.7 we reproduced this problem in Jira 7.11 too.

This can affect any status on the far right or far left for example if you leave out a to do status from the old workflow, the sprint report will not see that the issues were ever "started" and it will negatively affect burndown

Workaround

Modify the affect project's workflow, add changed status back, and map this status to a column in the project's agile board(respective to their position in the old board i.e. far right or far left) They do not need transitions to or from other statuses. In the example above Agile reporting is fixed by adding Resolved and Closed back to the affected project's workflow and mapping the statuses to the Done column accordingly. See attached screenshot.