Sprint issues all to backlog after upgrade Jira, but issues still in a Sprint

[Jasper]

Hi,

After upgrading to version 7.10 I found out that all my Sprints are 'cleared', at least.. there aren't issues visible in them anymore:

But there were issues in them before the upgrade and you can still see that when you search for a specific issue. The Sprint is visible in there:

The same when editing the issues:

This is happening to all my projects.. how to fix this? Because they are saved somewhere in the correct Sprint, but not visible or something like it.. 

[Tuncay Senturk _Snapbytes_]

Did you try (full) reindexing?

If it did not help, have a look at here.