XML export of Rank field at Issue Navigator return empty value

Some of our teams use the XML export at the issue navigator for their work. For their work the rank information in the XML is crucial.
This value has been exported correctly several weeks ago in an older Agile version. Now the (new) rank value is empty in the XML export while it is still beeing provided on the issue navigator screen, as you can see in the attached screenshots.

This problem seems to have occured before in
https://jira.atlassian.com/browse/GHS-4297