Steps to reproduce:

1. Create a sprint
2. Add a bunch of issues to it
3. Close one issue.
4. Observe that the issue is no longer listed in the sprint in plan mode
5. Start the sprint and reload the page
6. Observe that the issue is now listed in the sprint

Expected behavior, started and unstarted sprints should have consistent issue sets being displayed.

Note: When issues are cloned, it is very easy to forget they are already in a sprint, then when you close them out, they disappear from the plan board. This makes clone centric workflows very susceptible to this.