unstarted sprint is empty after upgrading

After in-place upgrading JIRA from 5.0.5 to 6.3.10, all issues on unstarted sprint are not displayed.

We can reproduce this problem with MySQL and PostgreSQL.

Step to reproduce

1. install JIRA 5.0.5(vanilla state)
2. install JIRA Agile 6.1.6
3. create project A
4. create issues in project A
5. create project B
6. create issues in project B
7. create scrum board A
8. create sprint on board A includes project A issues only
9. start sprint on board A
10. create scrum board B includes project B issues only
11. create sprint on board B (leave this sprint as unstarted)
12. shutdown JIRA 5.0.5
13. upgrade JIRA from 5.0.5 to 6.3.10 by rapid upgrade method(in-place DB upgrading) by linux 64bit installer
14. upgrading JIRA 5.0.5 to 6.3.10 completed
15. install JIRA Agile 6.6.13 via UPM
16. all issues are vanished in unstarted sprint on board B

Workaround
We discussed this problem with Atlassian Support team.
We found that this problem did not occur by manually upgrade method(using XML backup file), but it's inconvenient on large JIRA instances.